diff --git a/Lib/unittest/signals.py b/Lib/unittest/signals.py
index e6a5fc5..251b488 100644
--- a/Lib/unittest/signals.py
+++ b/Lib/unittest/signals.py
@@ -35,8 +35,13 @@ class _InterruptHandler(object):
         if self.called:
             self.default_handler(signum, frame)
         self.called = True
+        stopped = False
         for result in _results.keys():
             result.stop()
+            stopped = True
+        if not stopped:
+            # if there aren't any registered results, delegate immediately
+            self.default_handler(signum, frame)
 
 _results = weakref.WeakKeyDictionary()
 def registerResult(result):
diff --git a/Lib/unittest/test/test_break.py b/Lib/unittest/test/test_break.py
index 2c75019..ff9c69e 100644
--- a/Lib/unittest/test/test_break.py
+++ b/Lib/unittest/test/test_break.py
@@ -31,6 +31,9 @@ class TestBreak(unittest.TestCase):
         unittest.installHandler()
         self.assertNotEqual(signal.getsignal(signal.SIGINT), default_handler)
 
+        result = unittest.TestResult()
+        unittest.registerResult(result)
+
         try:
             pid = os.getpid()
             os.kill(pid, signal.SIGINT)
@@ -39,6 +42,22 @@ class TestBreak(unittest.TestCase):
 
         self.assertTrue(unittest.signals._interrupt_handler.called)
 
+    def testNoResultsRegistered(self):
+        # Can't use skipIf decorator because the signal handler may have
+        # been changed after defining this method.
+        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
+            self.skipTest("test requires SIGINT to not be ignored")
+
+        unittest.installHandler()
+
+        self.assertEqual(list(unittest.signals._results.keys()), [])
+
+        with self.assertRaises(KeyboardInterrupt):
+            pid = os.getpid()
+            os.kill(pid, signal.SIGINT)
+
+        self.assertTrue(unittest.signals._interrupt_handler.called)
+
     def testRegisterResult(self):
         result = unittest.TestResult()
         unittest.registerResult(result)