--- a/unittest_or_fail.py
+++ b/unittest_or_fail.py
@@ -10,7 +10,7 @@
     """
 
     def run(self, test):
-        result = super().run(test)
+        result = super(NonZeroTextTestRunner, self).run(test)
         if result.testsRun == 0 and not result.skipped:
             self.stream.writeln("No tests found -- failing")
             sys.exit(3)