diff --git a/tests/test_flip_image.py b/tests/test_flip_image.py
index 7d7ca5cb6ff8b2b9a1ffaa36ea75673dd77573e2..24d2a90d613f52bf2359f6b8f82930c522eb445a 100644
--- a/tests/test_flip_image.py
+++ b/tests/test_flip_image.py
@@ -24,13 +24,17 @@ class FlipImageTestCase(unittest.TestCase):
             os.path.join(
                 os.environ["UNIT_TEST_DATA_ROOT"],
                 "csst_proto/test_flip/input/image.txt",
-            )
+            ),
+            delimiter=",",
+            dtype=int,
         )
         image_answer = np.loadtxt(
             os.path.join(
                 os.environ["UNIT_TEST_DATA_ROOT"],
                 "csst_proto/test_flip/answer/flipped_image.txt",
-            )
+            ),
+            delimiter=",",
+            dtype=int,
         )
         self.assertIs(
             flip_image(image_input),