diff --git a/tests/basics/set_difference.py b/tests/basics/set_difference.py
index abfcbe7d63..97b63a8150 100644
--- a/tests/basics/set_difference.py
+++ b/tests/basics/set_difference.py
@@ -14,3 +14,6 @@ print(s.difference_update({1}))
 print(sorted(s))
 print(s.difference_update({1}, [2]))
 print(sorted(s))
+
+s.difference_update(s)
+print(s)