diff --git a/Tests/test_file_im.py b/Tests/test_file_im.py
index cfdb46097..38ee6c6fb 100644
--- a/Tests/test_file_im.py
+++ b/Tests/test_file_im.py
@@ -72,13 +72,16 @@ def test_eoferror():
 
 
 def test_roundtrip(tmp_path):
-    for mode in ["RGB", "P", "PA"]:
+    def roundtrip(mode):
         out = str(tmp_path / "temp.im")
         im = hopper(mode)
         im.save(out)
         with Image.open(out) as reread:
             assert_image_equal(reread, im)
 
+    for mode in ["RGB", "P", "PA"]:
+        roundtrip(mode)
+
 
 def test_save_unsupported_mode(tmp_path):
     out = str(tmp_path / "temp.im")