diff --git a/lib/mutant.rb b/lib/mutant.rb
index 078394dc..da59b95e 100644
--- a/lib/mutant.rb
+++ b/lib/mutant.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'benchmark'
 require 'set'
 require 'adamantium'
diff --git a/lib/mutant/cache.rb b/lib/mutant/cache.rb
index e4483224..e28fb9d7 100644
--- a/lib/mutant/cache.rb
+++ b/lib/mutant/cache.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # An AST cache
   class Cache
diff --git a/lib/mutant/cli.rb b/lib/mutant/cli.rb
index bf80ee73..db0e01b3 100644
--- a/lib/mutant/cli.rb
+++ b/lib/mutant/cli.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'optparse'
 
 module Mutant
diff --git a/lib/mutant/cli/classifier.rb b/lib/mutant/cli/classifier.rb
index 8bbaf6e9..91ec353c 100644
--- a/lib/mutant/cli/classifier.rb
+++ b/lib/mutant/cli/classifier.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class CLI
     # A classifier for input strings
diff --git a/lib/mutant/cli/classifier/method.rb b/lib/mutant/cli/classifier/method.rb
index c4353a0e..4bb9c93f 100644
--- a/lib/mutant/cli/classifier/method.rb
+++ b/lib/mutant/cli/classifier/method.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class CLI
     class Classifier
diff --git a/lib/mutant/cli/classifier/namespace.rb b/lib/mutant/cli/classifier/namespace.rb
index f065a788..27be7509 100644
--- a/lib/mutant/cli/classifier/namespace.rb
+++ b/lib/mutant/cli/classifier/namespace.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class CLI
     class Classifier
diff --git a/lib/mutant/cli/classifier/scope.rb b/lib/mutant/cli/classifier/scope.rb
index 81c4d350..ade1b81e 100644
--- a/lib/mutant/cli/classifier/scope.rb
+++ b/lib/mutant/cli/classifier/scope.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class CLI
     class Classifier
diff --git a/lib/mutant/color.rb b/lib/mutant/color.rb
index cb5ceb8e..2083e122 100644
--- a/lib/mutant/color.rb
+++ b/lib/mutant/color.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Class to colorize strings
   class Color
diff --git a/lib/mutant/config.rb b/lib/mutant/config.rb
index 43f4146b..47277312 100644
--- a/lib/mutant/config.rb
+++ b/lib/mutant/config.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # The configuration of a mutator run
   class Config
diff --git a/lib/mutant/constants.rb b/lib/mutant/constants.rb
index d9ba9415..b0f48368 100644
--- a/lib/mutant/constants.rb
+++ b/lib/mutant/constants.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
 
   METHOD_POSTFIX_EXPANSIONS = {
diff --git a/lib/mutant/context.rb b/lib/mutant/context.rb
index e3511aa6..3e7dc1f9 100644
--- a/lib/mutant/context.rb
+++ b/lib/mutant/context.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # An abstract context where mutations can be appied to.
   class Context
diff --git a/lib/mutant/context/scope.rb b/lib/mutant/context/scope.rb
index ed2793be..8907d01d 100644
--- a/lib/mutant/context/scope.rb
+++ b/lib/mutant/context/scope.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Context
     # Scope context for mutation (Class or Module)
diff --git a/lib/mutant/differ.rb b/lib/mutant/differ.rb
index 5df95f9a..9e144ce2 100644
--- a/lib/mutant/differ.rb
+++ b/lib/mutant/differ.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Class to create diffs from source code
   class Differ
diff --git a/lib/mutant/killer.rb b/lib/mutant/killer.rb
index f2291e94..c6b61fde 100644
--- a/lib/mutant/killer.rb
+++ b/lib/mutant/killer.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Abstract base class for mutant killers
   class Killer
diff --git a/lib/mutant/killer/forked.rb b/lib/mutant/killer/forked.rb
index 19565ffd..6495f165 100644
--- a/lib/mutant/killer/forked.rb
+++ b/lib/mutant/killer/forked.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Killer
 
diff --git a/lib/mutant/killer/forking.rb b/lib/mutant/killer/forking.rb
index 64286f19..ae5a6162 100644
--- a/lib/mutant/killer/forking.rb
+++ b/lib/mutant/killer/forking.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Killer
 
diff --git a/lib/mutant/killer/rspec.rb b/lib/mutant/killer/rspec.rb
index 2cdb4199..845c3d0a 100644
--- a/lib/mutant/killer/rspec.rb
+++ b/lib/mutant/killer/rspec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Killer
     # Runner for rspec tests
diff --git a/lib/mutant/killer/static.rb b/lib/mutant/killer/static.rb
index ca5d71dd..5b09e720 100644
--- a/lib/mutant/killer/static.rb
+++ b/lib/mutant/killer/static.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Killer
     # Abstract base class for killer with static result
diff --git a/lib/mutant/loader.rb b/lib/mutant/loader.rb
index 18b57e3d..77ef901b 100644
--- a/lib/mutant/loader.rb
+++ b/lib/mutant/loader.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Base class for code loaders
   class Loader
diff --git a/lib/mutant/matcher.rb b/lib/mutant/matcher.rb
index 4101c68d..d3bbe842 100644
--- a/lib/mutant/matcher.rb
+++ b/lib/mutant/matcher.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Abstract matcher to find subjects to mutate
   class Matcher
diff --git a/lib/mutant/matcher/chain.rb b/lib/mutant/matcher/chain.rb
index 4aec2fdf..ae242413 100644
--- a/lib/mutant/matcher/chain.rb
+++ b/lib/mutant/matcher/chain.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
     # A chain of matchers
diff --git a/lib/mutant/matcher/method.rb b/lib/mutant/matcher/method.rb
index 2ca3fdf3..cd6c54e8 100644
--- a/lib/mutant/matcher/method.rb
+++ b/lib/mutant/matcher/method.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
     # Matcher for subjects that are a specific method
diff --git a/lib/mutant/matcher/method/finder.rb b/lib/mutant/matcher/method/finder.rb
index 21fae4d5..6f8e51ea 100644
--- a/lib/mutant/matcher/method/finder.rb
+++ b/lib/mutant/matcher/method/finder.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
     class Method
diff --git a/lib/mutant/matcher/method/instance.rb b/lib/mutant/matcher/method/instance.rb
index cceed857..87b96003 100644
--- a/lib/mutant/matcher/method/instance.rb
+++ b/lib/mutant/matcher/method/instance.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
     class Method
diff --git a/lib/mutant/matcher/method/singleton.rb b/lib/mutant/matcher/method/singleton.rb
index f9b91d8a..46e4e8a9 100644
--- a/lib/mutant/matcher/method/singleton.rb
+++ b/lib/mutant/matcher/method/singleton.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
     class Method
diff --git a/lib/mutant/matcher/methods.rb b/lib/mutant/matcher/methods.rb
index 6f26f8fb..6bd05cc1 100644
--- a/lib/mutant/matcher/methods.rb
+++ b/lib/mutant/matcher/methods.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
     # Abstract base class for matcher that returns method subjects from scope
diff --git a/lib/mutant/matcher/namespace.rb b/lib/mutant/matcher/namespace.rb
index b03435dd..f67aa8fa 100644
--- a/lib/mutant/matcher/namespace.rb
+++ b/lib/mutant/matcher/namespace.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
 
diff --git a/lib/mutant/matcher/scope.rb b/lib/mutant/matcher/scope.rb
index aae70d64..6b179ff3 100644
--- a/lib/mutant/matcher/scope.rb
+++ b/lib/mutant/matcher/scope.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
     # Matcher for specific namespace
diff --git a/lib/mutant/mutation.rb b/lib/mutant/mutation.rb
index bda5cf08..4fb76543 100644
--- a/lib/mutant/mutation.rb
+++ b/lib/mutant/mutation.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Represent a mutated node with its subject
   class Mutation
diff --git a/lib/mutant/mutation/evil.rb b/lib/mutant/mutation/evil.rb
index 2a93c1e4..6222fb62 100644
--- a/lib/mutant/mutation/evil.rb
+++ b/lib/mutant/mutation/evil.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutation
     # Evul mutation
diff --git a/lib/mutant/mutation/filter.rb b/lib/mutant/mutation/filter.rb
index b5d3fc70..ca9f5b55 100644
--- a/lib/mutant/mutation/filter.rb
+++ b/lib/mutant/mutation/filter.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutation
     # Abstract filter for mutations
diff --git a/lib/mutant/mutation/filter/code.rb b/lib/mutant/mutation/filter/code.rb
index 084e7bf2..7d046d41 100644
--- a/lib/mutant/mutation/filter/code.rb
+++ b/lib/mutant/mutation/filter/code.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutation
     class Filter
diff --git a/lib/mutant/mutation/filter/regexp.rb b/lib/mutant/mutation/filter/regexp.rb
index 95a951f1..fcf4d0a4 100644
--- a/lib/mutant/mutation/filter/regexp.rb
+++ b/lib/mutant/mutation/filter/regexp.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutation
     class Filter
diff --git a/lib/mutant/mutation/filter/whitelist.rb b/lib/mutant/mutation/filter/whitelist.rb
index 85a69c31..4f056a28 100644
--- a/lib/mutant/mutation/filter/whitelist.rb
+++ b/lib/mutant/mutation/filter/whitelist.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutation
     class Filter
diff --git a/lib/mutant/mutation/neutral.rb b/lib/mutant/mutation/neutral.rb
index 0104cdc6..0eb40ac5 100644
--- a/lib/mutant/mutation/neutral.rb
+++ b/lib/mutant/mutation/neutral.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutation
     # Neutral mutation
diff --git a/lib/mutant/mutator.rb b/lib/mutant/mutator.rb
index f608320b..906399fe 100644
--- a/lib/mutant/mutator.rb
+++ b/lib/mutant/mutator.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Generator for mutations
   class Mutator
diff --git a/lib/mutant/mutator/node.rb b/lib/mutant/mutator/node.rb
index 7ded8853..64a54561 100644
--- a/lib/mutant/mutator/node.rb
+++ b/lib/mutant/mutator/node.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Generator for mutations
   class Mutator
diff --git a/lib/mutant/mutator/node/argument.rb b/lib/mutant/mutator/node/argument.rb
index f0c1f439..caf787d2 100644
--- a/lib/mutant/mutator/node/argument.rb
+++ b/lib/mutant/mutator/node/argument.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/arguments.rb b/lib/mutant/mutator/node/arguments.rb
index 1b37a6ea..0c853b4e 100644
--- a/lib/mutant/mutator/node/arguments.rb
+++ b/lib/mutant/mutator/node/arguments.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/begin.rb b/lib/mutant/mutator/node/begin.rb
index 23bf4e5e..796f3188 100644
--- a/lib/mutant/mutator/node/begin.rb
+++ b/lib/mutant/mutator/node/begin.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/block.rb b/lib/mutant/mutator/node/block.rb
index acc1b739..fecac4ba 100644
--- a/lib/mutant/mutator/node/block.rb
+++ b/lib/mutant/mutator/node/block.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/case.rb b/lib/mutant/mutator/node/case.rb
index 9e00a9da..4c42f29a 100644
--- a/lib/mutant/mutator/node/case.rb
+++ b/lib/mutant/mutator/node/case.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/connective/binary.rb b/lib/mutant/mutator/node/connective/binary.rb
index 62b5161e..df0c3a8c 100644
--- a/lib/mutant/mutator/node/connective/binary.rb
+++ b/lib/mutant/mutator/node/connective/binary.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/const.rb b/lib/mutant/mutator/node/const.rb
index 898e05ce..3d27264d 100644
--- a/lib/mutant/mutator/node/const.rb
+++ b/lib/mutant/mutator/node/const.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/define.rb b/lib/mutant/mutator/node/define.rb
index 7c91ed1c..47992788 100644
--- a/lib/mutant/mutator/node/define.rb
+++ b/lib/mutant/mutator/node/define.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/generic.rb b/lib/mutant/mutator/node/generic.rb
index fa6feccd..35d6ba2e 100644
--- a/lib/mutant/mutator/node/generic.rb
+++ b/lib/mutant/mutator/node/generic.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/if.rb b/lib/mutant/mutator/node/if.rb
index 178a7c11..8f1cc25b 100644
--- a/lib/mutant/mutator/node/if.rb
+++ b/lib/mutant/mutator/node/if.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal.rb b/lib/mutant/mutator/node/literal.rb
index 9b39bf00..02910874 100644
--- a/lib/mutant/mutator/node/literal.rb
+++ b/lib/mutant/mutator/node/literal.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/array.rb b/lib/mutant/mutator/node/literal/array.rb
index bb8008d9..c95ec2ca 100644
--- a/lib/mutant/mutator/node/literal/array.rb
+++ b/lib/mutant/mutator/node/literal/array.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/boolean.rb b/lib/mutant/mutator/node/literal/boolean.rb
index e57343a2..5c1717af 100644
--- a/lib/mutant/mutator/node/literal/boolean.rb
+++ b/lib/mutant/mutator/node/literal/boolean.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/dynamic.rb b/lib/mutant/mutator/node/literal/dynamic.rb
index b6a74285..cecee3bc 100644
--- a/lib/mutant/mutator/node/literal/dynamic.rb
+++ b/lib/mutant/mutator/node/literal/dynamic.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/fixnum.rb b/lib/mutant/mutator/node/literal/fixnum.rb
index 4d75eaf7..86436277 100644
--- a/lib/mutant/mutator/node/literal/fixnum.rb
+++ b/lib/mutant/mutator/node/literal/fixnum.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/float.rb b/lib/mutant/mutator/node/literal/float.rb
index 8a1a64eb..8c54bd70 100644
--- a/lib/mutant/mutator/node/literal/float.rb
+++ b/lib/mutant/mutator/node/literal/float.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/hash.rb b/lib/mutant/mutator/node/literal/hash.rb
index e368e8fb..8bb1163e 100644
--- a/lib/mutant/mutator/node/literal/hash.rb
+++ b/lib/mutant/mutator/node/literal/hash.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/nil.rb b/lib/mutant/mutator/node/literal/nil.rb
index 9ca2b011..1ceeadb5 100644
--- a/lib/mutant/mutator/node/literal/nil.rb
+++ b/lib/mutant/mutator/node/literal/nil.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/range.rb b/lib/mutant/mutator/node/literal/range.rb
index 9db113d7..9f3d8bad 100644
--- a/lib/mutant/mutator/node/literal/range.rb
+++ b/lib/mutant/mutator/node/literal/range.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/regex.rb b/lib/mutant/mutator/node/literal/regex.rb
index 23310870..ef5e9594 100644
--- a/lib/mutant/mutator/node/literal/regex.rb
+++ b/lib/mutant/mutator/node/literal/regex.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/string.rb b/lib/mutant/mutator/node/literal/string.rb
index 898c87aa..6abd8cf2 100644
--- a/lib/mutant/mutator/node/literal/string.rb
+++ b/lib/mutant/mutator/node/literal/string.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/literal/symbol.rb b/lib/mutant/mutator/node/literal/symbol.rb
index a77e85c0..ad1f4f62 100644
--- a/lib/mutant/mutator/node/literal/symbol.rb
+++ b/lib/mutant/mutator/node/literal/symbol.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/masgn.rb b/lib/mutant/mutator/node/masgn.rb
index 4e80e4e8..496ee67c 100644
--- a/lib/mutant/mutator/node/masgn.rb
+++ b/lib/mutant/mutator/node/masgn.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/mlhs.rb b/lib/mutant/mutator/node/mlhs.rb
index 3235f7ed..7bddc758 100644
--- a/lib/mutant/mutator/node/mlhs.rb
+++ b/lib/mutant/mutator/node/mlhs.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/named_value/access.rb b/lib/mutant/mutator/node/named_value/access.rb
index f34a8502..8c522181 100644
--- a/lib/mutant/mutator/node/named_value/access.rb
+++ b/lib/mutant/mutator/node/named_value/access.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/named_value/constant_assignment.rb b/lib/mutant/mutator/node/named_value/constant_assignment.rb
index 00a63ea7..e8e55a42 100644
--- a/lib/mutant/mutator/node/named_value/constant_assignment.rb
+++ b/lib/mutant/mutator/node/named_value/constant_assignment.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/named_value/variable_assignment.rb b/lib/mutant/mutator/node/named_value/variable_assignment.rb
index ad9d0478..3e55dbcf 100644
--- a/lib/mutant/mutator/node/named_value/variable_assignment.rb
+++ b/lib/mutant/mutator/node/named_value/variable_assignment.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/noop.rb b/lib/mutant/mutator/node/noop.rb
index 5f6178f7..4df9fbe8 100644
--- a/lib/mutant/mutator/node/noop.rb
+++ b/lib/mutant/mutator/node/noop.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/return.rb b/lib/mutant/mutator/node/return.rb
index 460b18e0..d38bc26d 100644
--- a/lib/mutant/mutator/node/return.rb
+++ b/lib/mutant/mutator/node/return.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/send.rb b/lib/mutant/mutator/node/send.rb
index c675feb9..b7e70aba 100644
--- a/lib/mutant/mutator/node/send.rb
+++ b/lib/mutant/mutator/node/send.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/send/binary.rb b/lib/mutant/mutator/node/send/binary.rb
index 2d8e14d0..2552f311 100644
--- a/lib/mutant/mutator/node/send/binary.rb
+++ b/lib/mutant/mutator/node/send/binary.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/splat.rb b/lib/mutant/mutator/node/splat.rb
index 7ff83388..f7bc87ae 100644
--- a/lib/mutant/mutator/node/splat.rb
+++ b/lib/mutant/mutator/node/splat.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/super.rb b/lib/mutant/mutator/node/super.rb
index 940f4883..530482dd 100644
--- a/lib/mutant/mutator/node/super.rb
+++ b/lib/mutant/mutator/node/super.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/when.rb b/lib/mutant/mutator/node/when.rb
index a0005812..b882ecc9 100644
--- a/lib/mutant/mutator/node/when.rb
+++ b/lib/mutant/mutator/node/when.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/while.rb b/lib/mutant/mutator/node/while.rb
index 1bb181d5..853973ca 100644
--- a/lib/mutant/mutator/node/while.rb
+++ b/lib/mutant/mutator/node/while.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/node/zsuper.rb b/lib/mutant/mutator/node/zsuper.rb
index 7e86e860..a27559d7 100644
--- a/lib/mutant/mutator/node/zsuper.rb
+++ b/lib/mutant/mutator/node/zsuper.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Node
diff --git a/lib/mutant/mutator/registry.rb b/lib/mutant/mutator/registry.rb
index 163468ae..c830f938 100644
--- a/lib/mutant/mutator/registry.rb
+++ b/lib/mutant/mutator/registry.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     # Registry for mutators
diff --git a/lib/mutant/mutator/util.rb b/lib/mutant/mutator/util.rb
index 738663f8..9b6317e0 100644
--- a/lib/mutant/mutator/util.rb
+++ b/lib/mutant/mutator/util.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     # Namespace for utility mutators
diff --git a/lib/mutant/mutator/util/array.rb b/lib/mutant/mutator/util/array.rb
index a7393840..fed11ec0 100644
--- a/lib/mutant/mutator/util/array.rb
+++ b/lib/mutant/mutator/util/array.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Util
diff --git a/lib/mutant/mutator/util/symbol.rb b/lib/mutant/mutator/util/symbol.rb
index 637f8359..8c943131 100644
--- a/lib/mutant/mutator/util/symbol.rb
+++ b/lib/mutant/mutator/util/symbol.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Mutator
     class Util
diff --git a/lib/mutant/node_helpers.rb b/lib/mutant/node_helpers.rb
index 4e317358..a16ad87c 100644
--- a/lib/mutant/node_helpers.rb
+++ b/lib/mutant/node_helpers.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Mixin for node helpers
   module NodeHelpers
diff --git a/lib/mutant/random.rb b/lib/mutant/random.rb
index 3e73cbc8..227277ae 100644
--- a/lib/mutant/random.rb
+++ b/lib/mutant/random.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Module for generating random values
   module Random
diff --git a/lib/mutant/reporter.rb b/lib/mutant/reporter.rb
index 9e35aca5..7572ed8d 100644
--- a/lib/mutant/reporter.rb
+++ b/lib/mutant/reporter.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Abstract base class for reporters
   class Reporter
diff --git a/lib/mutant/reporter/cli.rb b/lib/mutant/reporter/cli.rb
index eacb04db..f6a0f8bd 100644
--- a/lib/mutant/reporter/cli.rb
+++ b/lib/mutant/reporter/cli.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Reporter
     # Reporter that reports in human readable format
diff --git a/lib/mutant/reporter/cli/printer.rb b/lib/mutant/reporter/cli/printer.rb
index 3bc6de86..9d51fab0 100644
--- a/lib/mutant/reporter/cli/printer.rb
+++ b/lib/mutant/reporter/cli/printer.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Reporter
     class CLI
diff --git a/lib/mutant/reporter/cli/printer/config.rb b/lib/mutant/reporter/cli/printer/config.rb
index 48fac422..e864bde7 100644
--- a/lib/mutant/reporter/cli/printer/config.rb
+++ b/lib/mutant/reporter/cli/printer/config.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Reporter
     class CLI
diff --git a/lib/mutant/reporter/cli/printer/killer.rb b/lib/mutant/reporter/cli/printer/killer.rb
index 29099df9..368e36f3 100644
--- a/lib/mutant/reporter/cli/printer/killer.rb
+++ b/lib/mutant/reporter/cli/printer/killer.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Reporter
     class CLI
diff --git a/lib/mutant/reporter/cli/printer/mutation.rb b/lib/mutant/reporter/cli/printer/mutation.rb
index 90d2f60d..02237101 100644
--- a/lib/mutant/reporter/cli/printer/mutation.rb
+++ b/lib/mutant/reporter/cli/printer/mutation.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Reporter
     class CLI
diff --git a/lib/mutant/reporter/cli/printer/subject.rb b/lib/mutant/reporter/cli/printer/subject.rb
index e2360fe1..25554b79 100644
--- a/lib/mutant/reporter/cli/printer/subject.rb
+++ b/lib/mutant/reporter/cli/printer/subject.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Reporter
     class CLI
diff --git a/lib/mutant/reporter/null.rb b/lib/mutant/reporter/null.rb
index acc4ed27..40265d01 100644
--- a/lib/mutant/reporter/null.rb
+++ b/lib/mutant/reporter/null.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Reporter
 
diff --git a/lib/mutant/runner.rb b/lib/mutant/runner.rb
index f94472fb..5507775f 100644
--- a/lib/mutant/runner.rb
+++ b/lib/mutant/runner.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Runner baseclass
   class Runner
diff --git a/lib/mutant/runner/config.rb b/lib/mutant/runner/config.rb
index 35f2b3f9..92e18560 100644
--- a/lib/mutant/runner/config.rb
+++ b/lib/mutant/runner/config.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Runner
     # Runner for object config
diff --git a/lib/mutant/runner/mutation.rb b/lib/mutant/runner/mutation.rb
index 4fddc7aa..b6b8c2c3 100644
--- a/lib/mutant/runner/mutation.rb
+++ b/lib/mutant/runner/mutation.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Runner
     # Mutation runner
diff --git a/lib/mutant/runner/subject.rb b/lib/mutant/runner/subject.rb
index 4fd2a552..8ca0d63c 100644
--- a/lib/mutant/runner/subject.rb
+++ b/lib/mutant/runner/subject.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Runner
     # Subject specific runner
diff --git a/lib/mutant/singleton_methods.rb b/lib/mutant/singleton_methods.rb
index 6e773aa3..32d9cd95 100644
--- a/lib/mutant/singleton_methods.rb
+++ b/lib/mutant/singleton_methods.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 # Singleton methods are defined here so zombie can pick them up
 module Mutant
 
diff --git a/lib/mutant/strategy.rb b/lib/mutant/strategy.rb
index 99f1364b..eeed1848 100644
--- a/lib/mutant/strategy.rb
+++ b/lib/mutant/strategy.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
 
   # Abstract base class for killing strategies
diff --git a/lib/mutant/strategy/method_expansion.rb b/lib/mutant/strategy/method_expansion.rb
index f0b02a11..9e6629c5 100644
--- a/lib/mutant/strategy/method_expansion.rb
+++ b/lib/mutant/strategy/method_expansion.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Strategy
     module MethodExpansion
diff --git a/lib/mutant/strategy/rspec.rb b/lib/mutant/strategy/rspec.rb
index 4636b3fa..f2f658a6 100644
--- a/lib/mutant/strategy/rspec.rb
+++ b/lib/mutant/strategy/rspec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Strategy
 
diff --git a/lib/mutant/strategy/rspec/dm2.rb b/lib/mutant/strategy/rspec/dm2.rb
index 27f8dc31..43e84353 100644
--- a/lib/mutant/strategy/rspec/dm2.rb
+++ b/lib/mutant/strategy/rspec/dm2.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Strategy
     class Rspec
diff --git a/lib/mutant/strategy/rspec/dm2/lookup.rb b/lib/mutant/strategy/rspec/dm2/lookup.rb
index aa98ecdd..4de0568c 100644
--- a/lib/mutant/strategy/rspec/dm2/lookup.rb
+++ b/lib/mutant/strategy/rspec/dm2/lookup.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Strategy
     class Rspec
diff --git a/lib/mutant/strategy/rspec/dm2/lookup/method.rb b/lib/mutant/strategy/rspec/dm2/lookup/method.rb
index bbeb0bbe..bccf27f4 100644
--- a/lib/mutant/strategy/rspec/dm2/lookup/method.rb
+++ b/lib/mutant/strategy/rspec/dm2/lookup/method.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Strategy
     class Rspec
diff --git a/lib/mutant/strategy/static.rb b/lib/mutant/strategy/static.rb
index d7da151e..bcd9b2cd 100644
--- a/lib/mutant/strategy/static.rb
+++ b/lib/mutant/strategy/static.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Strategy
     # Static strategies
diff --git a/lib/mutant/subject.rb b/lib/mutant/subject.rb
index c8562cc2..c6013921 100644
--- a/lib/mutant/subject.rb
+++ b/lib/mutant/subject.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Subject of a mutation
   class Subject
diff --git a/lib/mutant/subject/method.rb b/lib/mutant/subject/method.rb
index c887b17d..2a73efd3 100644
--- a/lib/mutant/subject/method.rb
+++ b/lib/mutant/subject/method.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Subject
     # Abstract base class for method subjects
diff --git a/lib/mutant/subject/method/instance.rb b/lib/mutant/subject/method/instance.rb
index 78ec463f..d31f6e7d 100644
--- a/lib/mutant/subject/method/instance.rb
+++ b/lib/mutant/subject/method/instance.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Subject
     class Method
diff --git a/lib/mutant/subject/method/singleton.rb b/lib/mutant/subject/method/singleton.rb
index a3f230fd..ce5a1dc5 100644
--- a/lib/mutant/subject/method/singleton.rb
+++ b/lib/mutant/subject/method/singleton.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Subject
     class Method
diff --git a/lib/mutant/support/method_object.rb b/lib/mutant/support/method_object.rb
index 10c947d4..ffa72444 100644
--- a/lib/mutant/support/method_object.rb
+++ b/lib/mutant/support/method_object.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # A mixing to create method object semantics
   module MethodObject
diff --git a/lib/mutant/zombifier.rb b/lib/mutant/zombifier.rb
index 29b29837..d426d9f2 100644
--- a/lib/mutant/zombifier.rb
+++ b/lib/mutant/zombifier.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Zombifier namespace
   module Zombifier
diff --git a/spec/integration/mutant/rspec_killer_spec.rb b/spec/integration/mutant/rspec_killer_spec.rb
index bf2678af..0571ae09 100644
--- a/spec/integration/mutant/rspec_killer_spec.rb
+++ b/spec/integration/mutant/rspec_killer_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant, 'rspec integration' do
diff --git a/spec/integration/mutant/test_mutator_handles_types_spec.rb b/spec/integration/mutant/test_mutator_handles_types_spec.rb
index c82a0815..8e1662c8 100644
--- a/spec/integration/mutant/test_mutator_handles_types_spec.rb
+++ b/spec/integration/mutant/test_mutator_handles_types_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant do
diff --git a/spec/integration/mutant/zombie_spec.rb b/spec/integration/mutant/zombie_spec.rb
index c6b6e9df..d6e73e36 100644
--- a/spec/integration/mutant/zombie_spec.rb
+++ b/spec/integration/mutant/zombie_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant, 'as a zombie' do
diff --git a/spec/shared/method_matcher_behavior.rb b/spec/shared/method_matcher_behavior.rb
index c2e5bbf6..903baf22 100644
--- a/spec/shared/method_matcher_behavior.rb
+++ b/spec/shared/method_matcher_behavior.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 shared_examples_for 'a method matcher' do
 
   before { subject }
diff --git a/spec/shared/mutator_behavior.rb b/spec/shared/mutator_behavior.rb
index 2fd3d518..3a37b59c 100644
--- a/spec/shared/mutator_behavior.rb
+++ b/spec/shared/mutator_behavior.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 class Subject
 
   include Equalizer.new(:source)
diff --git a/spec/support/compress_helper.rb b/spec/support/compress_helper.rb
index 3e96dc7e..b7631bbe 100644
--- a/spec/support/compress_helper.rb
+++ b/spec/support/compress_helper.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module CompressHelper
   def strip_indent(string)
     lines       = string.lines
diff --git a/spec/support/ice_nine_config.rb b/spec/support/ice_nine_config.rb
index cc738345..187ef346 100644
--- a/spec/support/ice_nine_config.rb
+++ b/spec/support/ice_nine_config.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'ice_nine'
 
 module IceNine
diff --git a/spec/support/rspec.rb b/spec/support/rspec.rb
index a495f2de..fc8d31a4 100644
--- a/spec/support/rspec.rb
+++ b/spec/support/rspec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 # Patch rspec to allow nested execution
 module Rspec
   # Run block in clean rspec environment
diff --git a/spec/support/test_app.rb b/spec/support/test_app.rb
index 6ab5db3f..8cfda9af 100644
--- a/spec/support/test_app.rb
+++ b/spec/support/test_app.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module TestApp
   def self.root
     File.expand_path('../../../test_app', __FILE__)
diff --git a/spec/unit/mutant/class_methods/singleton_subclass_instance_spec.rb b/spec/unit/mutant/class_methods/singleton_subclass_instance_spec.rb
index 21fc8140..8c47fc40 100644
--- a/spec/unit/mutant/class_methods/singleton_subclass_instance_spec.rb
+++ b/spec/unit/mutant/class_methods/singleton_subclass_instance_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant, '.singleton_subclass_instance' do
diff --git a/spec/unit/mutant/cli/class_methods/new_spec.rb b/spec/unit/mutant/cli/class_methods/new_spec.rb
index 8ca8b662..b603edb4 100644
--- a/spec/unit/mutant/cli/class_methods/new_spec.rb
+++ b/spec/unit/mutant/cli/class_methods/new_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 shared_examples_for 'an invalid cli run' do
diff --git a/spec/unit/mutant/cli/class_methods/run_spec.rb b/spec/unit/mutant/cli/class_methods/run_spec.rb
index a8ff0a13..506c8b22 100644
--- a/spec/unit/mutant/cli/class_methods/run_spec.rb
+++ b/spec/unit/mutant/cli/class_methods/run_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::CLI, '.run' do
diff --git a/spec/unit/mutant/cli/classifier/class_methods/build_spec.rb b/spec/unit/mutant/cli/classifier/class_methods/build_spec.rb
index 81c21ae1..7229bced 100644
--- a/spec/unit/mutant/cli/classifier/class_methods/build_spec.rb
+++ b/spec/unit/mutant/cli/classifier/class_methods/build_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::CLI::Classifier, '.build' do
diff --git a/spec/unit/mutant/context/root_spec.rb b/spec/unit/mutant/context/root_spec.rb
index f1b3d4b6..74346da9 100644
--- a/spec/unit/mutant/context/root_spec.rb
+++ b/spec/unit/mutant/context/root_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Context, '#root' do
diff --git a/spec/unit/mutant/context/scope/root_spec.rb b/spec/unit/mutant/context/scope/root_spec.rb
index 0c3149c8..5559c873 100644
--- a/spec/unit/mutant/context/scope/root_spec.rb
+++ b/spec/unit/mutant/context/scope/root_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Context::Scope, '#root' do
diff --git a/spec/unit/mutant/context/scope/unqualified_name_spec.rb b/spec/unit/mutant/context/scope/unqualified_name_spec.rb
index b06f6baa..e4fda3d6 100644
--- a/spec/unit/mutant/context/scope/unqualified_name_spec.rb
+++ b/spec/unit/mutant/context/scope/unqualified_name_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Context::Scope, '#unqualified_name' do
diff --git a/spec/unit/mutant/differ/class_methods/build_spec.rb b/spec/unit/mutant/differ/class_methods/build_spec.rb
index 5679c8d4..a5d513d9 100644
--- a/spec/unit/mutant/differ/class_methods/build_spec.rb
+++ b/spec/unit/mutant/differ/class_methods/build_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Differ, '.build' do
diff --git a/spec/unit/mutant/differ/class_methods/colorize_line_spec.rb b/spec/unit/mutant/differ/class_methods/colorize_line_spec.rb
index 939e6ad2..cdd1fe55 100644
--- a/spec/unit/mutant/differ/class_methods/colorize_line_spec.rb
+++ b/spec/unit/mutant/differ/class_methods/colorize_line_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Differ, '.colorize_line' do
diff --git a/spec/unit/mutant/differ/diff_spec.rb b/spec/unit/mutant/differ/diff_spec.rb
index 063fc5f1..ba86f6b0 100644
--- a/spec/unit/mutant/differ/diff_spec.rb
+++ b/spec/unit/mutant/differ/diff_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Differ, '#diff' do
diff --git a/spec/unit/mutant/killer/rspec/class_methods/new_spec.rb b/spec/unit/mutant/killer/rspec/class_methods/new_spec.rb
index b7d72840..5081b326 100644
--- a/spec/unit/mutant/killer/rspec/class_methods/new_spec.rb
+++ b/spec/unit/mutant/killer/rspec/class_methods/new_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Killer::Rspec, '.new' do
diff --git a/spec/unit/mutant/killer/success_predicate_spec.rb b/spec/unit/mutant/killer/success_predicate_spec.rb
index 4c8e12b0..605d81ea 100644
--- a/spec/unit/mutant/killer/success_predicate_spec.rb
+++ b/spec/unit/mutant/killer/success_predicate_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Killer, '#success?' do
diff --git a/spec/unit/mutant/loader/eval/class_methods/run_spec.rb b/spec/unit/mutant/loader/eval/class_methods/run_spec.rb
index ce6cdc88..8c2f587f 100644
--- a/spec/unit/mutant/loader/eval/class_methods/run_spec.rb
+++ b/spec/unit/mutant/loader/eval/class_methods/run_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Loader::Eval, '.run' do
diff --git a/spec/unit/mutant/matcher/chain/each_spec.rb b/spec/unit/mutant/matcher/chain/each_spec.rb
index 517928ab..d3b37589 100644
--- a/spec/unit/mutant/matcher/chain/each_spec.rb
+++ b/spec/unit/mutant/matcher/chain/each_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Chain, '#each' do
diff --git a/spec/unit/mutant/matcher/chain/matchers_spec.rb b/spec/unit/mutant/matcher/chain/matchers_spec.rb
index d73a4d8e..bafee822 100644
--- a/spec/unit/mutant/matcher/chain/matchers_spec.rb
+++ b/spec/unit/mutant/matcher/chain/matchers_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Chain, '#matchers' do
diff --git a/spec/unit/mutant/matcher/each_spec.rb b/spec/unit/mutant/matcher/each_spec.rb
index 338e2961..bfe53d3d 100644
--- a/spec/unit/mutant/matcher/each_spec.rb
+++ b/spec/unit/mutant/matcher/each_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 # This spec is only present to ensure 100% test coverage.
diff --git a/spec/unit/mutant/matcher/method/instance/class_methods/build_spec.rb b/spec/unit/mutant/matcher/method/instance/class_methods/build_spec.rb
index b36f2f8d..deac7655 100644
--- a/spec/unit/mutant/matcher/method/instance/class_methods/build_spec.rb
+++ b/spec/unit/mutant/matcher/method/instance/class_methods/build_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Method::Instance, '.build' do
diff --git a/spec/unit/mutant/matcher/method/instance/each_spec.rb b/spec/unit/mutant/matcher/method/instance/each_spec.rb
index 0aa43716..7eb1f1b9 100644
--- a/spec/unit/mutant/matcher/method/instance/each_spec.rb
+++ b/spec/unit/mutant/matcher/method/instance/each_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Method::Instance, '#each' do
diff --git a/spec/unit/mutant/matcher/method/singleton/each_spec.rb b/spec/unit/mutant/matcher/method/singleton/each_spec.rb
index 08471581..940a049e 100644
--- a/spec/unit/mutant/matcher/method/singleton/each_spec.rb
+++ b/spec/unit/mutant/matcher/method/singleton/each_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Method::Singleton, '#each' do
diff --git a/spec/unit/mutant/matcher/methods/instance/each_spec.rb b/spec/unit/mutant/matcher/methods/instance/each_spec.rb
index 1e022ae1..b2d1b80e 100644
--- a/spec/unit/mutant/matcher/methods/instance/each_spec.rb
+++ b/spec/unit/mutant/matcher/methods/instance/each_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Methods::Instance, '#each' do
diff --git a/spec/unit/mutant/matcher/methods/singleton/each_spec.rb b/spec/unit/mutant/matcher/methods/singleton/each_spec.rb
index 2dad2aea..1c8edca2 100644
--- a/spec/unit/mutant/matcher/methods/singleton/each_spec.rb
+++ b/spec/unit/mutant/matcher/methods/singleton/each_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Methods::Singleton, '#each' do
diff --git a/spec/unit/mutant/matcher/namespace/each_spec.rb b/spec/unit/mutant/matcher/namespace/each_spec.rb
index f9942476..d8110cbe 100644
--- a/spec/unit/mutant/matcher/namespace/each_spec.rb
+++ b/spec/unit/mutant/matcher/namespace/each_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Namespace, '#each' do
diff --git a/spec/unit/mutant/mutator/each_spec.rb b/spec/unit/mutant/mutator/each_spec.rb
index a552fe31..db64797e 100644
--- a/spec/unit/mutant/mutator/each_spec.rb
+++ b/spec/unit/mutant/mutator/each_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 # This file is the sandbox for new mutations.
 # Once finished mutation test will be moved to class specfic
 # file.
diff --git a/spec/unit/mutant/mutator/emit_new_spec.rb b/spec/unit/mutant/mutator/emit_new_spec.rb
index e689092f..0ae0d070 100644
--- a/spec/unit/mutant/mutator/emit_new_spec.rb
+++ b/spec/unit/mutant/mutator/emit_new_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, '#emit_new' do
diff --git a/spec/unit/mutant/mutator/emit_spec.rb b/spec/unit/mutant/mutator/emit_spec.rb
index 30e3e231..243c8d38 100644
--- a/spec/unit/mutant/mutator/emit_spec.rb
+++ b/spec/unit/mutant/mutator/emit_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, '#emit' do
diff --git a/spec/unit/mutant/mutator/node/and_asgn/mutation_spec.rb b/spec/unit/mutant/mutator/node/and_asgn/mutation_spec.rb
index d10b7942..72d3eec7 100644
--- a/spec/unit/mutant/mutator/node/and_asgn/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/and_asgn/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'and_asgn' do
diff --git a/spec/unit/mutant/mutator/node/begin/mutation_spec.rb b/spec/unit/mutant/mutator/node/begin/mutation_spec.rb
index 00dbac87..15102206 100644
--- a/spec/unit/mutant/mutator/node/begin/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/begin/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, 'begin' do
diff --git a/spec/unit/mutant/mutator/node/block/mutation_spec.rb b/spec/unit/mutant/mutator/node/block/mutation_spec.rb
index e27088b0..0ac4de38 100644
--- a/spec/unit/mutant/mutator/node/block/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/block/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, 'block' do
diff --git a/spec/unit/mutant/mutator/node/block_pass/mutation_spec.rb b/spec/unit/mutant/mutator/node/block_pass/mutation_spec.rb
index 628a824c..702f8a5d 100644
--- a/spec/unit/mutant/mutator/node/block_pass/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/block_pass/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::NamedValue::Access, 'block_pass' do
diff --git a/spec/unit/mutant/mutator/node/break/mutation_spec.rb b/spec/unit/mutant/mutator/node/break/mutation_spec.rb
index 66b001a1..f15e15c3 100644
--- a/spec/unit/mutant/mutator/node/break/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/break/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'break' do
diff --git a/spec/unit/mutant/mutator/node/case/mutation_spec.rb b/spec/unit/mutant/mutator/node/case/mutation_spec.rb
index 28eb269b..6ec98923 100644
--- a/spec/unit/mutant/mutator/node/case/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/case/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Case do
diff --git a/spec/unit/mutant/mutator/node/cbase/mutation_spec.rb b/spec/unit/mutant/mutator/node/cbase/mutation_spec.rb
index b0239fb0..43638b04 100644
--- a/spec/unit/mutant/mutator/node/cbase/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/cbase/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Noop, 'cbase' do
diff --git a/spec/unit/mutant/mutator/node/connective/binary/mutation_spec.rb b/spec/unit/mutant/mutator/node/connective/binary/mutation_spec.rb
index a51012d1..29a8bfe9 100644
--- a/spec/unit/mutant/mutator/node/connective/binary/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/connective/binary/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Connective::Binary, 'mutations' do
diff --git a/spec/unit/mutant/mutator/node/const/mutation_spec.rb b/spec/unit/mutant/mutator/node/const/mutation_spec.rb
index 250f439e..07a79633 100644
--- a/spec/unit/mutant/mutator/node/const/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/const/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Const, 'const' do
diff --git a/spec/unit/mutant/mutator/node/define/mutation_spec.rb b/spec/unit/mutant/mutator/node/define/mutation_spec.rb
index 50fc8924..ac3de669 100644
--- a/spec/unit/mutant/mutator/node/define/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/define/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, 'def' do
diff --git a/spec/unit/mutant/mutator/node/defined_predicate/mutation_spec.rb b/spec/unit/mutant/mutator/node/defined_predicate/mutation_spec.rb
index e74bb23e..6ce3c8ed 100644
--- a/spec/unit/mutant/mutator/node/defined_predicate/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/defined_predicate/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'defined?' do
diff --git a/spec/unit/mutant/mutator/node/dstr/mutation_spec.rb b/spec/unit/mutant/mutator/node/dstr/mutation_spec.rb
index 6f2db551..08cac4d7 100644
--- a/spec/unit/mutant/mutator/node/dstr/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/dstr/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'dstr' do
diff --git a/spec/unit/mutant/mutator/node/dsym/mutation_spec.rb b/spec/unit/mutant/mutator/node/dsym/mutation_spec.rb
index d059f4cb..eed07c37 100644
--- a/spec/unit/mutant/mutator/node/dsym/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/dsym/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'dsum' do
diff --git a/spec/unit/mutant/mutator/node/ensure/mutation_spec.rb b/spec/unit/mutant/mutator/node/ensure/mutation_spec.rb
index 0a633170..827617c7 100644
--- a/spec/unit/mutant/mutator/node/ensure/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/ensure/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'ensure' do
diff --git a/spec/unit/mutant/mutator/node/if/mutation_spec.rb b/spec/unit/mutant/mutator/node/if/mutation_spec.rb
index bf05ae88..5f0c076e 100644
--- a/spec/unit/mutant/mutator/node/if/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/if/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, 'if' do
diff --git a/spec/unit/mutant/mutator/node/literal/array_spec.rb b/spec/unit/mutant/mutator/node/literal/array_spec.rb
index 5a94fccc..32798e69 100644
--- a/spec/unit/mutant/mutator/node/literal/array_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/array_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'array' do
diff --git a/spec/unit/mutant/mutator/node/literal/boolean/mutation_spec.rb b/spec/unit/mutant/mutator/node/literal/boolean/mutation_spec.rb
index 9b6f871b..344e2bdb 100644
--- a/spec/unit/mutant/mutator/node/literal/boolean/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/boolean/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'boolean' do
diff --git a/spec/unit/mutant/mutator/node/literal/fixnum_spec.rb b/spec/unit/mutant/mutator/node/literal/fixnum_spec.rb
index a69dc32b..795fc6d0 100644
--- a/spec/unit/mutant/mutator/node/literal/fixnum_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/fixnum_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'fixnum' do
diff --git a/spec/unit/mutant/mutator/node/literal/float_spec.rb b/spec/unit/mutant/mutator/node/literal/float_spec.rb
index 5c9c1861..4332cca8 100644
--- a/spec/unit/mutant/mutator/node/literal/float_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/float_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'float' do
diff --git a/spec/unit/mutant/mutator/node/literal/hash_spec.rb b/spec/unit/mutant/mutator/node/literal/hash_spec.rb
index 6e25b4e9..88e23451 100644
--- a/spec/unit/mutant/mutator/node/literal/hash_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/hash_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'hash' do
diff --git a/spec/unit/mutant/mutator/node/literal/nil_spec.rb b/spec/unit/mutant/mutator/node/literal/nil_spec.rb
index 759ae273..72fb2e54 100644
--- a/spec/unit/mutant/mutator/node/literal/nil_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/nil_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'nil' do
diff --git a/spec/unit/mutant/mutator/node/literal/range_spec.rb b/spec/unit/mutant/mutator/node/literal/range_spec.rb
index 94212698..1963b4ea 100644
--- a/spec/unit/mutant/mutator/node/literal/range_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/range_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'range' do
diff --git a/spec/unit/mutant/mutator/node/literal/regex_spec.rb b/spec/unit/mutant/mutator/node/literal/regex_spec.rb
index 07cdba40..8a3a1dce 100644
--- a/spec/unit/mutant/mutator/node/literal/regex_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/regex_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'regex' do
diff --git a/spec/unit/mutant/mutator/node/literal/string_spec.rb b/spec/unit/mutant/mutator/node/literal/string_spec.rb
index 1bb18c6d..b2fe6473 100644
--- a/spec/unit/mutant/mutator/node/literal/string_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/string_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'string' do
diff --git a/spec/unit/mutant/mutator/node/literal/symbol_spec.rb b/spec/unit/mutant/mutator/node/literal/symbol_spec.rb
index 9832e5f7..0acc656f 100644
--- a/spec/unit/mutant/mutator/node/literal/symbol_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/symbol_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'symbol' do
diff --git a/spec/unit/mutant/mutator/node/masgn/mutation_spec.rb b/spec/unit/mutant/mutator/node/masgn/mutation_spec.rb
index f9be3d7a..f1c94d63 100644
--- a/spec/unit/mutant/mutator/node/masgn/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/masgn/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, 'masgn' do
diff --git a/spec/unit/mutant/mutator/node/match_current_line/mutation_spec.rb b/spec/unit/mutant/mutator/node/match_current_line/mutation_spec.rb
index 09f65e2d..50e20117 100644
--- a/spec/unit/mutant/mutator/node/match_current_line/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/match_current_line/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'match_current_line' do
diff --git a/spec/unit/mutant/mutator/node/named_value/access/mutation_spec.rb b/spec/unit/mutant/mutator/node/named_value/access/mutation_spec.rb
index 75d02795..15d04bfb 100644
--- a/spec/unit/mutant/mutator/node/named_value/access/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/named_value/access/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::NamedValue::Access, 'mutations' do
diff --git a/spec/unit/mutant/mutator/node/named_value/constant_assignment/mutation_spec.rb b/spec/unit/mutant/mutator/node/named_value/constant_assignment/mutation_spec.rb
index 66454a71..45604ed4 100644
--- a/spec/unit/mutant/mutator/node/named_value/constant_assignment/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/named_value/constant_assignment/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::NamedValue::VariableAssignment, 'mutations' do
diff --git a/spec/unit/mutant/mutator/node/named_value/variable_assignment/mutation_spec.rb b/spec/unit/mutant/mutator/node/named_value/variable_assignment/mutation_spec.rb
index 219d2924..e06405c0 100644
--- a/spec/unit/mutant/mutator/node/named_value/variable_assignment/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/named_value/variable_assignment/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::NamedValue::VariableAssignment, 'mutations' do
diff --git a/spec/unit/mutant/mutator/node/next/mutation_spec.rb b/spec/unit/mutant/mutator/node/next/mutation_spec.rb
index b35506f8..a5fdeaaa 100644
--- a/spec/unit/mutant/mutator/node/next/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/next/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'next' do
diff --git a/spec/unit/mutant/mutator/node/op_assgn/mutation_spec.rb b/spec/unit/mutant/mutator/node/op_assgn/mutation_spec.rb
index dcff8e81..b44ddf5b 100644
--- a/spec/unit/mutant/mutator/node/op_assgn/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/op_assgn/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'op_asgn' do
diff --git a/spec/unit/mutant/mutator/node/or_asgn/mutation_spec.rb b/spec/unit/mutant/mutator/node/or_asgn/mutation_spec.rb
index 2c5b896b..e707a519 100644
--- a/spec/unit/mutant/mutator/node/or_asgn/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/or_asgn/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'or_asgn' do
diff --git a/spec/unit/mutant/mutator/node/redo/mutation_spec.rb b/spec/unit/mutant/mutator/node/redo/mutation_spec.rb
index 01deab52..9723a89d 100644
--- a/spec/unit/mutant/mutator/node/redo/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/redo/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'redo' do
diff --git a/spec/unit/mutant/mutator/node/rescue/mutation_spec.rb b/spec/unit/mutant/mutator/node/rescue/mutation_spec.rb
index e99b4576..91f6d14f 100644
--- a/spec/unit/mutant/mutator/node/rescue/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/rescue/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'rescue' do
diff --git a/spec/unit/mutant/mutator/node/restarg/mutation_spec.rb b/spec/unit/mutant/mutator/node/restarg/mutation_spec.rb
index 2ded7de0..8d325937 100644
--- a/spec/unit/mutant/mutator/node/restarg/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/restarg/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'restarg' do
diff --git a/spec/unit/mutant/mutator/node/return/mutation_spec.rb b/spec/unit/mutant/mutator/node/return/mutation_spec.rb
index 18cab57a..e099041c 100644
--- a/spec/unit/mutant/mutator/node/return/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/return/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, 'return' do
diff --git a/spec/unit/mutant/mutator/node/send/mutation_spec.rb b/spec/unit/mutant/mutator/node/send/mutation_spec.rb
index a841204a..83193bfc 100644
--- a/spec/unit/mutant/mutator/node/send/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/send/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 # FIXME: This spec needs to be structured better!
diff --git a/spec/unit/mutant/mutator/node/super/mutation_spec.rb b/spec/unit/mutant/mutator/node/super/mutation_spec.rb
index 0f3c9ed7..47304065 100644
--- a/spec/unit/mutant/mutator/node/super/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/super/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator, 'super' do
diff --git a/spec/unit/mutant/mutator/node/while/mutation_spec.rb b/spec/unit/mutant/mutator/node/while/mutation_spec.rb
index 9441e8c1..1b220ad7 100644
--- a/spec/unit/mutant/mutator/node/while/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/while/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::While do
diff --git a/spec/unit/mutant/mutator/node/yield/mutation_spec.rb b/spec/unit/mutant/mutator/node/yield/mutation_spec.rb
index 6d6eda68..47f096a6 100644
--- a/spec/unit/mutant/mutator/node/yield/mutation_spec.rb
+++ b/spec/unit/mutant/mutator/node/yield/mutation_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'yield' do
diff --git a/spec/unit/mutant/node_helpers/n_not_spec.rb b/spec/unit/mutant/node_helpers/n_not_spec.rb
index 6e737e27..3487a2f1 100644
--- a/spec/unit/mutant/node_helpers/n_not_spec.rb
+++ b/spec/unit/mutant/node_helpers/n_not_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::NodeHelpers, '#n_not' do
diff --git a/spec/unit/mutant/runner/config/subjects_spec.rb b/spec/unit/mutant/runner/config/subjects_spec.rb
index 6cce1580..f70cc19f 100644
--- a/spec/unit/mutant/runner/config/subjects_spec.rb
+++ b/spec/unit/mutant/runner/config/subjects_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Runner::Config, '#subjects' do
diff --git a/spec/unit/mutant/runner/config/success_predicate_spec.rb b/spec/unit/mutant/runner/config/success_predicate_spec.rb
index 0b437e64..3d1df834 100644
--- a/spec/unit/mutant/runner/config/success_predicate_spec.rb
+++ b/spec/unit/mutant/runner/config/success_predicate_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Runner::Config, '#success?' do
diff --git a/spec/unit/mutant/runner/mutation/killer_spec.rb b/spec/unit/mutant/runner/mutation/killer_spec.rb
index 2396d691..e7e0da13 100644
--- a/spec/unit/mutant/runner/mutation/killer_spec.rb
+++ b/spec/unit/mutant/runner/mutation/killer_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Runner::Mutation, '#killer' do
diff --git a/spec/unit/mutant/runner/subject/success_predicate_spec.rb b/spec/unit/mutant/runner/subject/success_predicate_spec.rb
index 58d21519..b0bbd55d 100644
--- a/spec/unit/mutant/runner/subject/success_predicate_spec.rb
+++ b/spec/unit/mutant/runner/subject/success_predicate_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Runner::Subject, '#success?' do
diff --git a/spec/unit/mutant/strategy/method_expansion/class_methods/run_spec.rb b/spec/unit/mutant/strategy/method_expansion/class_methods/run_spec.rb
index 1a15269c..e9c08888 100644
--- a/spec/unit/mutant/strategy/method_expansion/class_methods/run_spec.rb
+++ b/spec/unit/mutant/strategy/method_expansion/class_methods/run_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Strategy::MethodExpansion, '.run' do
diff --git a/spec/unit/mutant/strategy/rspec/dm2/lookup/method/instance/spec_files_spec.rb b/spec/unit/mutant/strategy/rspec/dm2/lookup/method/instance/spec_files_spec.rb
index ab1ce701..a86c6c96 100644
--- a/spec/unit/mutant/strategy/rspec/dm2/lookup/method/instance/spec_files_spec.rb
+++ b/spec/unit/mutant/strategy/rspec/dm2/lookup/method/instance/spec_files_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 singleton = Mutant::Strategy::Rspec::DM2::Lookup::Method::Instance
diff --git a/spec/unit/mutant/strategy/rspec/dm2/lookup/method/singleton/spec_files_spec.rb b/spec/unit/mutant/strategy/rspec/dm2/lookup/method/singleton/spec_files_spec.rb
index 3023bac3..9e0f7964 100644
--- a/spec/unit/mutant/strategy/rspec/dm2/lookup/method/singleton/spec_files_spec.rb
+++ b/spec/unit/mutant/strategy/rspec/dm2/lookup/method/singleton/spec_files_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 singleton = Mutant::Strategy::Rspec::DM2::Lookup::Method::Singleton
diff --git a/spec/unit/mutant/subject/context_spec.rb b/spec/unit/mutant/subject/context_spec.rb
index 1e173c27..c7d1173f 100644
--- a/spec/unit/mutant/subject/context_spec.rb
+++ b/spec/unit/mutant/subject/context_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Subject, '#context' do
diff --git a/spec/unit/mutant/subject/mutations_spec.rb b/spec/unit/mutant/subject/mutations_spec.rb
index c54e3ff6..38159102 100644
--- a/spec/unit/mutant/subject/mutations_spec.rb
+++ b/spec/unit/mutant/subject/mutations_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Subject, '#mutations' do
diff --git a/spec/unit/mutant/subject/node_spec.rb b/spec/unit/mutant/subject/node_spec.rb
index 302e84f4..29f38224 100644
--- a/spec/unit/mutant/subject/node_spec.rb
+++ b/spec/unit/mutant/subject/node_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Subject, '#node' do
diff --git a/test_app/lib/test_app.rb b/test_app/lib/test_app.rb
index 1723b090..0df5bbc0 100644
--- a/test_app/lib/test_app.rb
+++ b/test_app/lib/test_app.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 # Namespace for test application
 module TestApp
 end
diff --git a/test_app/lib/test_app/literal.rb b/test_app/lib/test_app/literal.rb
index 025a726c..691b3bca 100644
--- a/test_app/lib/test_app/literal.rb
+++ b/test_app/lib/test_app/literal.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module TestApp
   # Class for integration testing literal mutations
   class Literal
diff --git a/test_app/spec/shared/method_filter_parse_behavior.rb b/test_app/spec/shared/method_filter_parse_behavior.rb
index 99cb867e..0cddb85d 100644
--- a/test_app/spec/shared/method_filter_parse_behavior.rb
+++ b/test_app/spec/shared/method_filter_parse_behavior.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 shared_examples_for 'a method filter parse result' do
   before do
     expected_class.stub(:new => response)
diff --git a/test_app/spec/shared/method_match_behavior.rb b/test_app/spec/shared/method_match_behavior.rb
index c9b16eec..cf50bf51 100644
--- a/test_app/spec/shared/method_match_behavior.rb
+++ b/test_app/spec/shared/method_match_behavior.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 shared_examples_for 'a method match' do
   subject { Mutant::Matcher::Method.parse(pattern).to_a }
 
diff --git a/test_app/spec/unit/test_app/literal/command_spec.rb b/test_app/spec/unit/test_app/literal/command_spec.rb
index 338929c0..8f8a8beb 100644
--- a/test_app/spec/unit/test_app/literal/command_spec.rb
+++ b/test_app/spec/unit/test_app/literal/command_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe TestApp::Literal, '#string' do
diff --git a/test_app/spec/unit/test_app/literal/string_spec.rb b/test_app/spec/unit/test_app/literal/string_spec.rb
index 8704f1e7..b05a421a 100644
--- a/test_app/spec/unit/test_app/literal/string_spec.rb
+++ b/test_app/spec/unit/test_app/literal/string_spec.rb
@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe TestApp::Literal, '#string' do