diff --git a/lib/mutant.rb b/lib/mutant.rb
index 6246945fe..6b156c6a0 100644
--- a/lib/mutant.rb
+++ b/lib/mutant.rb
@@ -246,6 +246,7 @@ module Mutant
     require 'mutant/repository'
     require 'mutant/repository/diff'
     require 'mutant/repository/diff/ranges'
+    require 'mutant/repository/file_revision'
     require 'mutant/zombifier'
     require 'mutant/range'
     require 'mutant/license'
@@ -319,6 +320,7 @@ module Mutant
     mutex:                 Mutex,
     object_space:          ObjectSpace,
     open3:                 Open3,
+    parser:                Parser.new,
     pathname:              Pathname,
     process:               Process,
     random:                Random,
diff --git a/lib/mutant/cli/command/environment.rb b/lib/mutant/cli/command/environment.rb
index a10194c26..c1fd09748 100644
--- a/lib/mutant/cli/command/environment.rb
+++ b/lib/mutant/cli/command/environment.rb
@@ -102,11 +102,13 @@ def add_matcher_options(parser)
           parser.on('--start-subject EXPRESSION', 'Start mutation testing at a specific subject') do |pattern|
             add_matcher(:start_expressions, @config.expression_parser.call(pattern).from_right)
           end
-          parser.on('--since REVISION', 'Only select subjects touched since REVISION') do |revision|
+          parser.on('--since REVISION', 'Only select dirty subjects since REVISION') do |revision|
             add_matcher(
               :subject_filters,
               Repository::SubjectFilter.new(
-                Repository::Diff.new(to: revision, world: world)
+                diff:     Repository::Diff.new(to: revision, world: world),
+                revision: revision,
+                world:    world
               )
             )
           end
diff --git a/lib/mutant/env.rb b/lib/mutant/env.rb
index abc17dc68..a485f0ba5 100644
--- a/lib/mutant/env.rb
+++ b/lib/mutant/env.rb
@@ -9,7 +9,6 @@ class Env
       :integration,
       :matchable_scopes,
       :mutations,
-      :parser,
       :selector,
       :subjects,
       :world
@@ -37,7 +36,6 @@ def self.empty(world, config)
         ),
         matchable_scopes: EMPTY_ARRAY,
         mutations:        EMPTY_ARRAY,
-        parser:           Parser.new,
         selector:         Selector::Null.new,
         subjects:         EMPTY_ARRAY,
         world:            world
@@ -64,6 +62,13 @@ def cover_index(mutation_index)
       )
     end
 
+    # The parser
+    #
+    # @return [Parser]
+    def parser
+      world.parser
+    end
+
     # The test selections
     #
     # @return Hash{Mutation => Enumerable<Test>}
diff --git a/lib/mutant/repository.rb b/lib/mutant/repository.rb
index fb1fc3965..dd7f15a7d 100644
--- a/lib/mutant/repository.rb
+++ b/lib/mutant/repository.rb
@@ -4,7 +4,7 @@ module Mutant
   module Repository
     # Subject filter based on repository diff
     class SubjectFilter
-      include Adamantium, Concord.new(:diff)
+      include Adamantium, Anima.new(:diff, :revision, :world)
 
       # Test if subject was touched in diff
       #
diff --git a/lib/mutant/repository/file_revision.rb b/lib/mutant/repository/file_revision.rb
new file mode 100644
index 000000000..11191502a
--- /dev/null
+++ b/lib/mutant/repository/file_revision.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module Mutant
+  module Repository
+    class FileRevision
+      def self.read(world:, revision:, file_name:)
+        world
+          .capture_stdout(%w[git show #{revision}:#{file_name}])
+      end
+    end # FileRevision
+  end # Repository
+end # Mutant
diff --git a/lib/mutant/world.rb b/lib/mutant/world.rb
index 2677735eb..57abae954 100644
--- a/lib/mutant/world.rb
+++ b/lib/mutant/world.rb
@@ -16,6 +16,7 @@ class World
       :mutex,
       :object_space,
       :open3,
+      :parser,
       :pathname,
       :process,
       :random,
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 0d07aafcb..fe218d26f 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -114,6 +114,7 @@ def fake_world
       mutex:                 class_double(Mutex),
       object_space:          class_double(ObjectSpace),
       open3:                 class_double(Open3),
+      parser:                class_double(Mutant::Parser),
       pathname:              class_double(Pathname),
       process:               class_double(Process),
       random:                class_double(Random),
diff --git a/spec/unit/mutant/bootstrap_spec.rb b/spec/unit/mutant/bootstrap_spec.rb
index 1c77ab7cc..dc4b05778 100644
--- a/spec/unit/mutant/bootstrap_spec.rb
+++ b/spec/unit/mutant/bootstrap_spec.rb
@@ -56,6 +56,7 @@ def require(_); end
       kernel:                kernel,
       load_path:             load_path,
       object_space:          object_space,
+      parser:                Mutant::Parser.new,
       pathname:              Pathname,
       recorder:              instance_double(Mutant::Segment::Recorder),
       timer:                 timer
diff --git a/spec/unit/mutant/cli_spec.rb b/spec/unit/mutant/cli_spec.rb
index 611fa5fc8..605495ab8 100644
--- a/spec/unit/mutant/cli_spec.rb
+++ b/spec/unit/mutant/cli_spec.rb
@@ -301,7 +301,7 @@ def self.main_body
         Matcher:
                 --ignore-subject EXPRESSION  Ignore subjects that match EXPRESSION as prefix
                 --start-subject EXPRESSION   Start mutation testing at a specific subject
-                --since REVISION             Only select subjects touched since REVISION
+                --since REVISION             Only select dirty subjects since REVISION
       MESSAGE
 
       {
@@ -348,7 +348,7 @@ def self.main_body
         Matcher:
                 --ignore-subject EXPRESSION  Ignore subjects that match EXPRESSION as prefix
                 --start-subject EXPRESSION   Start mutation testing at a specific subject
-                --since REVISION             Only select subjects touched since REVISION
+                --since REVISION             Only select dirty subjects since REVISION
       MESSAGE
 
       {
@@ -395,7 +395,7 @@ def self.main_body
         Matcher:
                 --ignore-subject EXPRESSION  Ignore subjects that match EXPRESSION as prefix
                 --start-subject EXPRESSION   Start mutation testing at a specific subject
-                --since REVISION             Only select subjects touched since REVISION
+                --since REVISION             Only select dirty subjects since REVISION
       MESSAGE
 
       {
@@ -1290,10 +1290,12 @@ def self.main_body
               matcher: file_config.matcher.with(
                 subject_filters: [
                   Mutant::Repository::SubjectFilter.new(
-                    Mutant::Repository::Diff.new(
+                    diff:     Mutant::Repository::Diff.new(
                       to:    'reference',
                       world: world
-                    )
+                    ),
+                    revision: 'reference',
+                    world:    world
                   )
                 ]
               )
@@ -1305,10 +1307,12 @@ def self.main_body
               matcher: file_config.matcher.with(
                 subject_filters: [
                   Mutant::Repository::SubjectFilter.new(
-                    Mutant::Repository::Diff.new(
+                    diff:     Mutant::Repository::Diff.new(
                       to:    'reference',
                       world: world
-                    )
+                    ),
+                    revision: 'reference',
+                    world:    world
                   )
                 ]
               )
diff --git a/spec/unit/mutant/env_spec.rb b/spec/unit/mutant/env_spec.rb
index 1feb011d8..58f4b618d 100644
--- a/spec/unit/mutant/env_spec.rb
+++ b/spec/unit/mutant/env_spec.rb
@@ -8,7 +8,6 @@
       integration:      integration,
       matchable_scopes: [],
       mutations:        [mutation],
-      parser:           Mutant::Parser.new,
       selector:         selector,
       subjects:         subjects,
       world:            world
@@ -239,7 +238,6 @@ def apply
           integration:      integration,
           matchable_scopes: Mutant::EMPTY_ARRAY,
           mutations:        Mutant::EMPTY_ARRAY,
-          parser:           Mutant::Parser.new,
           selector:         Mutant::Selector::Null.new,
           subjects:         Mutant::EMPTY_ARRAY,
           world:            world
@@ -268,4 +266,10 @@ def apply
       expect(events).to eql([%i[test_segment value]])
     end
   end
+
+  describe '#parser' do
+    it 'returns the world parser' do
+      expect(subject.parser).to be(world.parser)
+    end
+  end
 end
diff --git a/spec/unit/mutant/repository/subject_filter_spec.rb b/spec/unit/mutant/repository/subject_filter_spec.rb
index 797911cb3..608742665 100644
--- a/spec/unit/mutant/repository/subject_filter_spec.rb
+++ b/spec/unit/mutant/repository/subject_filter_spec.rb
@@ -2,11 +2,19 @@
 
 RSpec.describe Mutant::Repository::SubjectFilter do
   context '#call' do
-    subject { object.call(mutant_subject) }
+    def apply
+      subject.call(mutant_subject)
+    end
 
-    let(:object) { described_class.new(diff)                 }
-    let(:diff)   { instance_double(Mutant::Repository::Diff) }
-    let(:value)  { instance_double(Object, 'value')          }
+    subject do
+      described_class.new(
+        diff:     diff,
+        revision: 'revision',
+        world:    fake_world
+      )
+    end
+
+    let(:diff) { instance_double(Mutant::Repository::Diff) }
 
     let(:mutant_subject) do
       double(
@@ -20,11 +28,15 @@
       expect(diff).to receive(:touches?).with(
         mutant_subject.source_path,
         mutant_subject.source_lines
-      ).and_return(value)
+      ).and_return(touches?)
     end
 
-    it 'connects return value to repository diff API' do
-      expect(subject).to be(value)
+    context 'when subject lines are not touched' do
+      let(:touches?) { false }
+
+      it 'returns false' do
+        expect(apply).to be(false)
+      end
     end
   end
 end