diff --git a/lib/mutant/diff.rb b/lib/mutant/diff.rb
index 382c93d2..72d6b1c6 100644
--- a/lib/mutant/diff.rb
+++ b/lib/mutant/diff.rb
@@ -64,7 +64,7 @@ module Mutant
     # @api private
     #
     def self.lines(source)
-      source.lines.map { |line| line.chomp }
+      source.lines.map(&:chomp)
     end
     private_class_method :lines