diff --git a/kallithea/controllers/compare.py b/kallithea/controllers/compare.py
--- a/kallithea/controllers/compare.py
+++ b/kallithea/controllers/compare.py
@@ -272,7 +272,7 @@ class CompareController(BaseRepoControll
                                       ignore_whitespace=ignore_whitespace,
                                       context=line_context)
 
-        diff_processor = diffs.DiffProcessor(raw_diff or '', diff_limit=diff_limit)
+        diff_processor = diffs.DiffProcessor(raw_diff, diff_limit=diff_limit)
         c.limited_diff = diff_processor.limited_diff
         c.file_diff_data = []
         c.lines_added = 0