diff --git a/Gemfile.devtools b/Gemfile.devtools
index 9696b9fa..91c7518d 100644
--- a/Gemfile.devtools
+++ b/Gemfile.devtools
@@ -3,7 +3,7 @@
 group :development do
   gem 'rake',  '~> 10.0.4'
   gem 'rspec', '~> 2.13.0'
-  gem 'yard',  '~> 0.8.5.2'
+  gem 'yard',  '~> 0.8.6'
 end
 
 group :yard do
@@ -13,7 +13,7 @@ end
 group :guard do
   gem 'guard',         '~> 1.7.0'
   gem 'guard-bundler', '~> 1.0.0'
-  gem 'guard-rspec',   '~> 2.5.2'
+  gem 'guard-rspec',   '~> 2.5.3'
 
   # file system change event handling
   gem 'listen',     '~> 0.7.3'
@@ -29,12 +29,12 @@ end
 
 group :metrics do
   gem 'backports',       '~> 3.3', '>= 3.3.0'
-  gem 'coveralls',       '~> 0.6.4'
-  gem 'flay',            '~> 2.1.0'
+  gem 'coveralls',       '~> 0.6.5'
+  gem 'flay',            '~> 2.2.0'
   gem 'flog',            '~> 3.2.3'
   gem 'reek',            '~> 1.3.1', :git => 'https://github.com/troessner/reek.git'
   gem 'simplecov',       '~> 0.7.1'
-  gem 'yardstick',       '~> 0.9.5'
+  gem 'yardstick',       '~> 0.9.6'
   gem 'yard-spellcheck', '~> 0.1.5'
 
   platforms :rbx do
diff --git a/config/flay.yml b/config/flay.yml
index 1fbb7d1a..e5817985 100644
--- a/config/flay.yml
+++ b/config/flay.yml
@@ -1,3 +1,3 @@
 ---
-threshold: 25 # Todo bring down to ~20
-total_score: 914
+threshold: 16
+total_score: 577
diff --git a/config/flog.yml b/config/flog.yml
index 5704a723..0b91a104 100644
--- a/config/flog.yml
+++ b/config/flog.yml
@@ -1,2 +1,2 @@
 ---
-threshold: 44.0
+threshold: 37.6
diff --git a/config/reek.yml b/config/reek.yml
new file mode 100644
index 00000000..66fc2169
--- /dev/null
+++ b/config/reek.yml
@@ -0,0 +1,196 @@
+---
+Attribute:
+  enabled: true
+  exclude:
+  - Mutant::CLI::Classifier
+  - Mutant::Context
+  - Mutant::Context::Scope
+  - Mutant::Killer
+  - Mutant::Killer::Forking
+  - Mutant::Matcher::Chain
+  - Mutant::Matcher::Method
+  - Mutant::Matcher::Methods
+  - Mutant::Matcher::Namespace
+  - Mutant::Mutation
+  - Mutant::Mutation::Filter::Code
+  - Mutant::Mutation::Filter::Whitelist
+  - Mutant::Mutator
+  - Mutant::Reporter
+  - Mutant::Reporter::CLI
+  - Mutant::Reporter::Stats
+  - Mutant::Reporter::Stats::Counter
+  - Mutant::Runner
+  - Mutant::Runner::Config
+  - Mutant::Runner::Mutation
+  - Mutant::Runner::Subject
+  - Mutant::Strategy
+  - Mutant::Strategy::Rspec::DM2::Lookup
+  - Mutant::Subject
+BooleanParameter:
+  enabled: true
+  exclude: []
+ClassVariable:
+  enabled: true
+  exclude: []
+ControlParameter:
+  enabled: true
+  exclude: []
+DataClump:
+  enabled: true
+  exclude: []
+  max_copies: 2
+  min_clump_size: 2
+DuplicateMethodCall:
+  enabled: true
+  exclude:
+  - Mutant::CLI::Classifier::Method#method
+  - Mutant::Killer#run_with_benchmark
+  - Mutant::Mutator::Node::FormalArguments19::DefaultMutations#dispatch
+  - Mutant::Mutator::Node::FormalArguments19::RequireDefaults#dispatch
+  - Mutant::Mutator::Node::Literal::Hash#emit_element_presence
+  - Mutant::Mutator::Node::Send::WithArguments#emit_argument_mutations
+  - Mutant::Reporter::CLI#colorized_diff
+  - Mutant::Reporter::CLI#report_killer
+  - Mutant::Runner::Config#run
+  max_calls: 1
+  allow_calls: []
+FeatureEnvy:
+  enabled: true
+  exclude:
+  - Mutant::Matcher::Method::Instance#match?
+  - Mutant::Matcher::Namespace#emit_scope_matches
+  - Mutant::Mutation::Evil#success?
+  - Mutant::Mutation::Neutral#success?
+  - Mutant::Mutator::Node::DefaultArguments#dispatch
+  - Mutant::Mutator::Node::FormalArguments19#emit_required_mutations
+  - Mutant::Mutator::Node::FormalArguments19::DefaultMutations#dispatch
+  - Mutant::Mutator::Node::FormalArguments19::RequireDefaults#dispatch
+  - Mutant::Mutator::Node::PatternArguments#allow?
+  - Mutant::Reporter::CLI#report_killer
+  - Mutant::Reporter::CLI#start
+IrresponsibleModule:
+  enabled: true
+  exclude:
+  - Mutant::Matcher::Methods::Instance
+  - Mutant::Mutator::Node::Define
+  - Mutant::Mutator::Node::DefineSingleton
+  - Mutant::Strategy::Rspec::DM2::Lookup::Method
+  - Mutant::Strategy::Rspec::DM2::Lookup::Method::Instance
+  - Mutant::Strategy::Rspec::DM2::Lookup::Method::Singleton
+LongParameterList:
+  enabled: true
+  exclude:
+  - Mutant::Mutator::Node#new_send_with_arguments
+  max_params: 2
+  overrides:
+    initialize:
+      max_params: 3
+LongYieldList:
+  enabled: true
+  exclude: []
+  max_params: 2
+NestedIterators:
+  enabled: true
+  exclude:
+  - Mutant#self.define_singleton_subclass
+  - Mutant::Mutator::Node::FormalArguments19::PatternArgumentExpansion#dispatch
+  - Mutant::Mutator::Node::FormalArguments19::RequireDefaults#dispatch
+  - Mutant::Mutator::Node::ReceiverCase#emit_when_branch_mutations
+  - Mutant::Mutator::Util::Array::Element#dispatch
+  max_allowed_nesting: 1
+  ignore_iterators: []
+NilCheck:
+  enabled: true
+  exclude:
+  - Mutant::Matcher::Method#skip?
+RepeatedConditional:
+  enabled: true
+  exclude:
+  - Mutant::Reporter::CLI
+  max_ifs: 1
+TooManyInstanceVariables:
+  enabled: true
+  exclude:
+  - Mutant::CLI
+  - Mutant::Killer
+  max_instance_variables: 3
+TooManyMethods:
+  enabled: true
+  exclude:
+  - Mutant::CLI
+  - Mutant::Matcher::Method
+  - Mutant::Reporter::CLI
+  max_methods: 10
+TooManyStatements:
+  enabled: true
+  exclude:
+  - Mutant#self.define_singleton_subclass
+  - Mutant::CLI#self.run
+  - Mutant::Differ#diff
+  - Mutant::Killer::Forked#run
+  - Mutant::Mutator::Node#emit_attribute_mutations
+  - Mutant::Mutator::Node::FormalArguments19::DefaultMutations#dispatch
+  - Mutant::Mutator::Node::FormalArguments19::PatternArgumentExpansion#dispatch
+  - Mutant::Mutator::Node::FormalArguments19::RequireDefaults#dispatch
+  - Mutant::Mutator::Node::If#dispatch
+  - Mutant::Reporter::CLI#colorized_diff
+  - Mutant::Reporter::CLI#report_killer
+  - Mutant::Reporter::CLI#start
+  - each
+  max_statements: 5
+UncommunicativeMethodName:
+  enabled: true
+  exclude:
+  - Mutant::Mutation#sha1
+  reject:
+  - !ruby/regexp /^[a-z]$/
+  - !ruby/regexp /[0-9]$/
+  - !ruby/regexp /[A-Z]/
+  accept: []
+UncommunicativeModuleName:
+  enabled: true
+  exclude:
+  - Mutant::Mutator::Node::FormalArguments19
+  - Mutant::Mutator::Node::Iter19
+  - Mutant::Strategy::Rspec::DM2
+  reject:
+  - !ruby/regexp /^.$/
+  - !ruby/regexp /[0-9]$/
+  accept: []
+UncommunicativeParameterName:
+  enabled: true
+  exclude: []
+  reject:
+  - !ruby/regexp /^.$/
+  - !ruby/regexp /[0-9]$/
+  - !ruby/regexp /[A-Z]/
+  accept: []
+UncommunicativeVariableName:
+  enabled: true
+  exclude: []
+  reject:
+  - !ruby/regexp /^.$/
+  - !ruby/regexp /[0-9]$/
+  - !ruby/regexp /[A-Z]/
+  accept: []
+UnusedParameters:
+  enabled: true
+  exclude:
+  - Mutant::Mutation::Filter#match?
+  - Mutant::Mutation::Filter#self.handle
+  - Mutant::Mutator#allow?
+  - Mutant::Strategy::Rspec::Full#spec_files
+  - Mutant::Strategy::Rspec::Integration#spec_files
+  - Mutant::Strategy::Rspec::Unit#spec_files
+UtilityFunction:
+  enabled: true
+  exclude:
+  - Mutant::Matcher::Namespace#emit_scope_matches
+  - Mutant::Mutation::Evil#success?
+  - Mutant::Mutation::Neutral#success?
+  - Mutant::Mutator::Node::PatternArguments#allow?
+  - Mutant::Strategy::Rspec::DM2#spec_files
+  - Mutant::Strategy::Rspec::Full#spec_files
+  - Mutant::Strategy::Rspec::Integration#spec_files
+  - Mutant::Strategy::Rspec::Unit#spec_files
+  max_helper_calls: 0
diff --git a/config/roodi.yml b/config/roodi.yml
deleted file mode 100644
index 522e1fe3..00000000
--- a/config/roodi.yml
+++ /dev/null
@@ -1,26 +0,0 @@
----
-AbcMetricMethodCheck:
-  score: 12.2
-AssignmentInConditionalCheck:    {}
-CaseMissingElseCheck:            {}
-ClassLineCountCheck:
-  line_count: 324
-ClassNameCheck:
-  pattern: !ruby/regexp /\A(?:[A-Z]+|[A-Z][a-z](?:[A-Z]?[a-z])+)\z/
-ClassVariableCheck:              {}
-CyclomaticComplexityBlockCheck:
-  complexity: 2
-CyclomaticComplexityMethodCheck:
-  complexity: 4
-EmptyRescueBodyCheck:            {}
-ForLoopCheck:                    {}
-MethodLineCountCheck:
-  line_count: 9
-MethodNameCheck:
-  pattern: !ruby/regexp /\A(?:[a-z\d](?:_?[a-z\d])+[?!=]?|\[\]=?|==|<=>|<<|[+*&|-])\z/
-ModuleLineCountCheck:
-  line_count: 327
-ModuleNameCheck:
-  pattern: !ruby/regexp /\A(?:[A-Z]+|[A-Z][a-z](?:[A-Z]?[a-z])+)\z/
-ParameterNumberCheck:
-  parameter_count: 3
diff --git a/config/site.reek b/config/site.reek
deleted file mode 100644
index 2406b1c4..00000000
--- a/config/site.reek
+++ /dev/null
@@ -1,104 +0,0 @@
----
-UncommunicativeParameterName:
-  accept: []
-  exclude: []
-  enabled: true
-  reject:
-  - !ruby/regexp /^.$/
-  - !ruby/regexp /[0-9]$/
-  - !ruby/regexp /[A-Z]/
-LargeClass:
-  max_methods: 10
-  exclude:
-  - "Mutant::Reporter::CLI" # 16 methods TODO Reduce!
-  - "Mutant::Reporter::Stats" # 6 ivars TODO Reduce!
-  - "Mutant::CLI" # 19 methods and 7 ivars, TODO Reduce!
-  enabled: true
-  max_instance_variables: 3
-UncommunicativeMethodName:
-  accept:
-  - sha1
-  exclude: []
-  enabled: true
-  reject:
-  - !ruby/regexp /^[a-z]$/
-  - !ruby/regexp /[0-9]$/
-  - !ruby/regexp /[A-Z]/
-LongParameterList:
-  max_params: 2
-  exclude:
-  - "Mutant::Mutator::Node#new_send_with_arguments" # 3 params
-  - "Mutant::Context::Constant#initialize" # 3 params
-  - "Mutant::Subject#initialize" # 3 params
-  enabled: true
-  overrides: {}
-FeatureEnvy:
-  exclude: []
-  enabled: true
-ClassVariable:
-  exclude: []
-  enabled: true
-BooleanParameter:
-  exclude: []
-  enabled: true
-IrresponsibleModule:
-  exclude: []
-  enabled: true
-UncommunicativeModuleName:
-  accept:
-  - Mutant::Mutator::Node::Iter19
-  - Mutant::Strategy::Rspec::DM2
-  exclude: []
-  enabled: true
-  reject:
-  - !ruby/regexp /^.$/
-  - !ruby/regexp /[0-9]$/
-NestedIterators:
-  ignore_iterators: []
-  exclude:
-  - Mutant#self.define_singleton_subclass
-  - Mutant::Mutator::Util::Array::Element#dispatch
-  - Mutant::Mutator::Node::ReceiverCase#emit_when_branch_mutation
-  enabled: true
-  max_allowed_nesting: 1
-LongMethod:
-  max_statements: 6
-  exclude: []
-  enabled: true
-Duplication:
-  allow_calls: []
-  exclude:
-  - Mutant::Mutator::Node::Literal::Hash#emit_element_presence
-  enabled: true
-  max_calls: 1
-UtilityFunction:
-  max_helper_calls: 0
-  exclude: []
-  enabled: true
-Attribute:
-  exclude: []
-  enabled: false
-UncommunicativeVariableName:
-  accept: []
-  exclude: []
-  enabled: true
-  reject:
-  - !ruby/regexp /^.$/
-  - !ruby/regexp /[0-9]$/
-  - !ruby/regexp /[A-Z]/
-SimulatedPolymorphism:
-  exclude: []
-  enabled: true
-  max_ifs: 1
-DataClump:
-  exclude: []
-  enabled: true
-  max_copies: 2
-  min_clump_size: 2
-ControlCouple:
-  exclude: []
-  enabled: true
-LongYieldList:
-  max_params: 1
-  exclude: []
-  enabled: true
diff --git a/lib/mutant/cli.rb b/lib/mutant/cli.rb
index 4cd89880..2f27cfe2 100644
--- a/lib/mutant/cli.rb
+++ b/lib/mutant/cli.rb
@@ -157,7 +157,8 @@ module Mutant
     def dispatch_matcher
       argument = current_argument
       consume(1)
-      @matchers << Classifier.build(argument)
+      matcher = Classifier.build(argument)
+      @matchers << matcher if matcher
     end
 
     # Process option argument
diff --git a/lib/mutant/killer/forked.rb b/lib/mutant/killer/forked.rb
index fe839d04..4f790ddb 100644
--- a/lib/mutant/killer/forked.rb
+++ b/lib/mutant/killer/forked.rb
@@ -33,7 +33,7 @@ module Mutant
         fork do
           begin
             killer = @killer.new(strategy, mutation)
-            Kernel.exit(killer.fail? ? 1 : 0)
+            Kernel.exit(killer.success? ? 0 : 1)
           rescue
             Kernel.exit(1)
           end
diff --git a/lib/mutant/killer/rspec.rb b/lib/mutant/killer/rspec.rb
index efb05908..80c2c901 100644
--- a/lib/mutant/killer/rspec.rb
+++ b/lib/mutant/killer/rspec.rb
@@ -17,7 +17,10 @@ module Mutant
       #
       def run
         mutation.insert
-        !!::RSpec::Core::Runner.run(command_line_arguments, strategy.error_stream, strategy.output_stream).nonzero?
+        # TODO: replace with real streams from configuration
+        require 'stringio'
+        null = StringIO.new
+        !::RSpec::Core::Runner.run(command_line_arguments, null, null).zero?
       end
 
       # Return command line arguments
diff --git a/lib/mutant/mutation.rb b/lib/mutant/mutation.rb
index a3fa6b49..98e54ae4 100644
--- a/lib/mutant/mutation.rb
+++ b/lib/mutant/mutation.rb
@@ -97,7 +97,7 @@ module Mutant
     # @api private
     #
     def sha1
-      Digest::SHA1.hexdigest(subject.identification + source)
+      Digest::SHA1.hexdigest(subject.identification + 0.chr + source)
     end
     memoize :sha1
 
diff --git a/lib/mutant/reporter/stats.rb b/lib/mutant/reporter/stats.rb
index 73a6595b..7b0afc9f 100644
--- a/lib/mutant/reporter/stats.rb
+++ b/lib/mutant/reporter/stats.rb
@@ -8,6 +8,12 @@ module Mutant
       class Counter
         include Equalizer.new(:count, :fails)
 
+        # Return count
+        #
+        # @return [Fixnum]
+        #
+        # @api private
+        #
         attr_reader :count
 
         # Return fail count
@@ -105,6 +111,8 @@ module Mutant
       # @return [false]
       #   otherwise
       #
+      # @api private
+      #
       def success?
         @counts[:subject].nonzero? && !errors?
       end
@@ -131,6 +139,8 @@ module Mutant
       # @return [false]
       #   otherwise
       #
+      # @api private
+      #
       def errors?
         @killers.values.any? do |counter|
           counter.nonzero?
diff --git a/lib/mutant/runner/subject.rb b/lib/mutant/runner/subject.rb
index 1352f522..d6e40d37 100644
--- a/lib/mutant/runner/subject.rb
+++ b/lib/mutant/runner/subject.rb
@@ -68,7 +68,7 @@ module Mutant
       # @api private
       #
       def run
-        @mutations = subject.mutations.map do |mutation|
+        @mutations = subject.map do |mutation|
           Mutation.run(config, mutation)
         end
       end
diff --git a/spec/unit/mutant/runner/subject/mutations_spec.rb b/spec/unit/mutant/runner/subject/mutations_spec.rb
deleted file mode 100644
index d46b857f..00000000
--- a/spec/unit/mutant/runner/subject/mutations_spec.rb
+++ /dev/null
@@ -1,24 +0,0 @@
-require 'spec_helper'
-
-describe Mutant::Runner::Subject, '#mutations' do
-  let(:object) { described_class.run(config, mutation_subject) }
-
-  subject { object.mutations }
-
-  let(:config)           { mock('Config')                            }
-  let(:mutation)         { mock('Mutation')                          }
-  let(:mutation_subject) { mock('Subject', :mutations => [mutation]) }
-
-  class DummyRunner
-    include Concord.new(:config, :mutation)
-    def self.run(*args); new(*args); end
-  end
-
-  before do
-    stub_const('Mutant::Runner::Mutation', DummyRunner)
-  end
-
-  it { should eql([DummyRunner.new(config, mutation)]) }
-
-  it_should_behave_like 'an idempotent method'
-end
diff --git a/spec/unit/mutant/runner/subject/success_predicate_spec.rb b/spec/unit/mutant/runner/subject/success_predicate_spec.rb
index 05e14a4e..916a1ded 100644
--- a/spec/unit/mutant/runner/subject/success_predicate_spec.rb
+++ b/spec/unit/mutant/runner/subject/success_predicate_spec.rb
@@ -5,11 +5,11 @@ describe Mutant::Runner::Subject, '#success?' do
 
   let(:object) { described_class.run(config, mutation_subject) }
 
-  let(:mutation_subject) { mock('Subject', :mutations => mutations) }
-  let(:config)           { mock('Config')                           }
-  let(:mutation_a)       { mock('Mutation A', :fails? => false)     }
-  let(:mutation_b)       { mock('Mutation B', :fails? => false)     }
-  let(:mutations)        { [mutation_a, mutation_b]                 }
+  let(:mutation_subject) { mock('Subject', :map => mutations)    }
+  let(:config)           { mock('Config')                        }
+  let(:mutation_a)       { mock('Mutation A', :failed? => false) }
+  let(:mutation_b)       { mock('Mutation B', :failed? => false) }
+  let(:mutations)        { [mutation_a, mutation_b]              }
 
   class DummyMutationRunner
     include Concord.new(:config, :mutation)
@@ -19,7 +19,7 @@ describe Mutant::Runner::Subject, '#success?' do
     end
 
     def failed?
-      @mutation.fails?
+      @mutation.failed?
     end
   end
 
@@ -36,7 +36,7 @@ describe Mutant::Runner::Subject, '#success?' do
 
   context 'with failing evil mutations' do
     before do
-      mutation_a.stub(:fails? => true)
+      mutation_a.stub(:failed? => true)
     end
 
     it { should be(false) }