diff --git a/Tests/test_imagedraw.py b/Tests/test_imagedraw.py
index 7c7a77dfa95..f6c5f009100 100644
--- a/Tests/test_imagedraw.py
+++ b/Tests/test_imagedraw.py
@@ -744,7 +744,7 @@ def test_rectangle_I16(bbox):
     draw = ImageDraw.Draw(im)
 
     # Act
-    draw.rectangle(bbox, outline=0xffff)
+    draw.rectangle(bbox, outline=0xFFFF)
 
     # Assert
     assert_image_equal_tofile(im.convert("I"), "Tests/images/imagedraw_rectangle_I.png")