diff --git a/Tests/helper.py b/Tests/helper.py
index 69246bfcf..62f07b9b6 100644
--- a/Tests/helper.py
+++ b/Tests/helper.py
@@ -95,7 +95,7 @@ def assert_image_equal(a, b, msg=None):
             except Exception:
                 pass
 
-        assert False, msg or "got different content"
+        assert a.tobytes() == b.tobytes(), msg or "got different content"
 
 
 def assert_image_equal_tofile(a, filename, msg=None, mode=None):