diff --git a/tests/test_flip_image.py b/tests/test_flip_image.py
index 24d2a90d613f52bf2359f6b8f82930c522eb445a..e247f337436ae3dd08b5c0f3552a0413ace83944 100644
--- a/tests/test_flip_image.py
+++ b/tests/test_flip_image.py
@@ -36,7 +36,7 @@ class FlipImageTestCase(unittest.TestCase):
             delimiter=",",
             dtype=int,
         )
-        self.assertIs(
+        self.assertEqual(
             flip_image(image_input),
             image_answer,
             "Test flip image on server failed",