diff --git a/lib/rubocop/git/runner.rb b/lib/rubocop/git/runner.rb
index a33d63e..846dd8b 100644
--- a/lib/rubocop/git/runner.rb
+++ b/lib/rubocop/git/runner.rb
@@ -33,7 +33,7 @@ def pull_request
       end
 
       def git_diff(options)
-        args = %w(diff --diff-filter=AMCR --find-renames --find-copies)
+        args = %w(-c diff.mnemonicprefix=false diff --no-color --diff-filter=AMCR --find-renames --find-copies)
 
         args << '--cached' if options.cached
         args << options.commit_first.shellescape if options.commit_first