diff --git a/app/controllers/projects/merge_requests_controller.rb b/app/controllers/projects/merge_requests_controller.rb
index 6189de09f2770238c6f22318cca977c6691b5c2d..785dcecc9beb9dc7c1e60e6383a153c81efec8e5 100644
--- a/app/controllers/projects/merge_requests_controller.rb
+++ b/app/controllers/projects/merge_requests_controller.rb
@@ -57,8 +57,8 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     respond_to do |format|
       format.html
       format.json { render json: @merge_request }
-      format.diff { render text: @merge_request.to_diff(current_user) }
-      format.patch { render text: @merge_request.to_patch(current_user) }
+      format.diff { render text: @merge_request.to_diff }
+      format.patch { render text: @merge_request.to_patch }
     end
   end
 
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index 7c61a7ae18c7a4c23722289fb734ad34993e2a09..b12a878327d27ca50920333a3593e41ef169dade 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -331,15 +331,15 @@ class MergeRequest < ActiveRecord::Base
   # Returns the raw diff for this merge request
   #
   # see "git diff"
-  def to_diff(current_user)
-    target_project.repository.diff_text(target_branch, source_sha)
+  def to_diff
+    target_project.repository.diff_text(diff_base_commit, source_sha)
   end
 
   # Returns the commit as a series of email patches.
   #
   # see "git format-patch"
-  def to_patch(current_user)
-    target_project.repository.format_patch(target_branch, source_sha)
+  def to_patch
+    target_project.repository.format_patch(diff_base_commit, source_sha)
   end
 
   def hook_attrs