diff --git a/lib/mutant/mutator/node/begin.rb b/lib/mutant/mutator/node/begin.rb
index c69dbc74..40f0da71 100644
--- a/lib/mutant/mutator/node/begin.rb
+++ b/lib/mutant/mutator/node/begin.rb
@@ -16,9 +16,7 @@ module Mutant
         # @api private
         #
         def dispatch
-          Util::Array.each(children, self) do |children|
-            emit_child_subset(children)
-          end
+          Util::Array.each(children, self, &method(:emit_child_subset))
           children.each_with_index do |child, index|
             mutate_child(index)
             emit(child) unless children.eql?([child])
diff --git a/lib/mutant/mutator/node/if.rb b/lib/mutant/mutator/node/if.rb
index 2d6a78de..7130e877 100644
--- a/lib/mutant/mutator/node/if.rb
+++ b/lib/mutant/mutator/node/if.rb
@@ -30,8 +30,8 @@ module Mutant
         # @api private
         #
         def mutate_condition
-          emit_condition_mutations do |condition|
-            !n_self?(condition)
+          emit_condition_mutations do |node|
+            !n_self?(node)
           end
           emit_type(n_not(condition), if_branch, else_branch) unless n_match_current_line?(condition)
           emit_type(N_TRUE,  if_branch, else_branch)
diff --git a/spec/unit/mutant/matcher/filter_spec.rb b/spec/unit/mutant/matcher/filter_spec.rb
index 8f6ee7f6..6b4393e2 100644
--- a/spec/unit/mutant/matcher/filter_spec.rb
+++ b/spec/unit/mutant/matcher/filter_spec.rb
@@ -6,7 +6,7 @@ RSpec.describe Mutant::Matcher::Filter do
     subject { object.each { |entry| yields << entry } }
 
     let(:matcher)   { [subject_a, subject_b] }
-    let(:predicate) { ->(subject) { subject.eql?(subject_a) } }
+    let(:predicate) { ->(node) { node.eql?(subject_a) } }
 
     let(:subject_a) { double('Subject A') }
     let(:subject_b) { double('Subject B') }
diff --git a/spec/unit/mutant/matcher/method/instance_spec.rb b/spec/unit/mutant/matcher/method/instance_spec.rb
index 0c398cb2..00fc9817 100644
--- a/spec/unit/mutant/matcher/method/instance_spec.rb
+++ b/spec/unit/mutant/matcher/method/instance_spec.rb
@@ -5,7 +5,7 @@ RSpec.describe Mutant::Matcher::Method::Instance do
   let(:reporter) { Fixtures::TEST_CONFIG.reporter }
 
   describe '#each' do
-    subject { object.each { |subject| yields << subject } }
+    subject { object.each(&yields.method(:<<)) }
 
     let(:object)       { described_class.build(env, scope, method) }
     let(:method)       { scope.instance_method(method_name)        }
diff --git a/spec/unit/mutant/matcher/method/singleton_spec.rb b/spec/unit/mutant/matcher/method/singleton_spec.rb
index a48b4195..3f3b9b2d 100644
--- a/spec/unit/mutant/matcher/method/singleton_spec.rb
+++ b/spec/unit/mutant/matcher/method/singleton_spec.rb
@@ -1,6 +1,6 @@
 # rubocop:disable ClassAndModuleChildren
 RSpec.describe Mutant::Matcher::Method::Singleton, '#each' do
-  subject { object.each { |subject| yields << subject } }
+  subject { object.each(&yields.method(:<<)) }
 
   let(:object)       { described_class.new(env, scope, method) }
   let(:method)       { scope.method(method_name)               }
diff --git a/spec/unit/mutant/require_highjack_spec.rb b/spec/unit/mutant/require_highjack_spec.rb
index a54dadc4..f68aed70 100644
--- a/spec/unit/mutant/require_highjack_spec.rb
+++ b/spec/unit/mutant/require_highjack_spec.rb
@@ -5,11 +5,9 @@ RSpec.describe Mutant::RequireHighjack do
   let(:require_calls)    { [] }
 
   let(:target) do
-    require_calls = self.require_calls
+    acc = require_calls
     Module.new do
-      define_method(:require) do |logical_name|
-        require_calls << logical_name
-      end
+      define_method(:require, &acc.method(:<<))
       module_function :require
     end
   end
diff --git a/spec/unit/mutant/warning_filter_spec.rb b/spec/unit/mutant/warning_filter_spec.rb
index 78c14bdf..24f6669d 100644
--- a/spec/unit/mutant/warning_filter_spec.rb
+++ b/spec/unit/mutant/warning_filter_spec.rb
@@ -8,11 +8,9 @@ RSpec.describe Mutant::WarningFilter do
   let(:object) { described_class.new(target) }
 
   let(:target) do
-    writes = self.writes
+    acc = writes
     Module.new do
-      define_singleton_method :write do |message|
-        writes << message
-      end
+      define_singleton_method(:write, &acc.method(:<<))
     end
   end