diff --git a/Tests/test_imagefile.py b/Tests/test_imagefile.py
index 7719c7c71..6964d3e00 100644
--- a/Tests/test_imagefile.py
+++ b/Tests/test_imagefile.py
@@ -95,8 +95,9 @@ class TestImageFile:
 
     def test_raise_ioerror(self):
         with pytest.raises(IOError):
-            with pytest.warns(DeprecationWarning):
+            with pytest.warns(DeprecationWarning) as record:
                 ImageFile.raise_ioerror(1)
+        assert len(record) == 1
 
     def test_raise_oserror(self):
         with pytest.raises(OSError):