diff --git a/boards/models/attachment/__init__.py b/boards/models/attachment/__init__.py
--- a/boards/models/attachment/__init__.py
+++ b/boards/models/attachment/__init__.py
@@ -82,8 +82,14 @@ class AttachmentManager(models.Manager):
                     chunk2ended = True
 
             if chunk1ended and chunk2ended:
+                # Same size chunksm checked for equality previously
+                break
+            elif chunk1ended or chunk2ended:
+                # Different size chunks, not equal
+                equal = False
                 break
             elif chunk1[position1] != chunk2[position2]:
+                # Different bytes, not equal
                 equal = False
                 break
             else: