--- a/src/twisted/test/test_failure.py
+++ b/src/twisted/test/test_failure.py
@@ -22,7 +22,7 @@
 from twisted.trial.unittest import SynchronousTestCase
 
 
-from cython_test_exception_raiser import raiser  # type: ignore[import]
+raiser = None
 
 
 def getDivisionFailure(*args, **kwargs):