1 files changed, 6 insertions, 2 deletions
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index 204d2b153ad..7eb875f1ef5 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -203,7 +203,11 @@ class MergeRequest < ActiveRecord::Base
   end
 
   def diff_size
-    opts = diff_options || {}
+    # The `#diffs` method ends up at an instance of a class inheriting from
+    # `Gitlab::Diff::FileCollection::Base`, so use those options as defaults
+    # here too, to get the same diff size without performing highlighting.
+    #
+    opts = Gitlab::Diff::FileCollection::Base.default_options.merge(diff_options || {})
 
     raw_diffs(opts).size
   end
@@ -527,7 +531,7 @@ class MergeRequest < ActiveRecord::Base
     }
 
     if diff_head_commit
-      attrs.merge!(last_commit: diff_head_commit.hook_attrs)
+      attrs[:last_commit] = diff_head_commit.hook_attrs
     end
 
     attributes.merge!(attrs)