diff --git a/reviewboard/diffviewer/filediff_creator.py b/reviewboard/diffviewer/filediff_creator.py
index 201772bf9075a2c33bd0d83b448f41f41ebecd38..8cbc3d486e2d7716013968593b54dc4bfe5b8f7f 100644
--- a/reviewboard/diffviewer/filediff_creator.py
+++ b/reviewboard/diffviewer/filediff_creator.py
@@ -204,10 +204,10 @@ def create_filediffs(diff_file_contents, parent_diff_file_contents,
             extra_data.update({
                 FileDiff._IS_PARENT_EMPTY_KEY: parent_is_empty,
                 'parent_source_filename':
-                    convert_to_unicode(parent_source_filename,
+                    convert_to_unicode(force_text(parent_source_filename),
                                        encoding_list)[1],
                 'parent_source_revision':
-                    convert_to_unicode(parent_source_revision,
+                    convert_to_unicode(force_text(parent_source_revision),
                                        encoding_list)[1],
             })