diff --git a/lib/gitlab/diff/parallel_diff.rb b/lib/gitlab/diff/parallel_diff.rb
index 0cb26fa45c8acd8b7b39a1be268fb600a7449b2e..cb962b735e44c8a067cd55132837ac615f946659 100644
--- a/lib/gitlab/diff/parallel_diff.rb
+++ b/lib/gitlab/diff/parallel_diff.rb
@@ -39,7 +39,6 @@ module Gitlab
                 right: line
               }
 
-              free_right_index = nil
               i += 1
             end
           elsif line.meta? || line.unchanged?