diff --git a/Lib/test/test_signal.py b/Lib/test/test_signal.py
index bd43511..9f997be 100644
--- a/Lib/test/test_signal.py
+++ b/Lib/test/test_signal.py
@@ -360,11 +360,14 @@
         signal.signal(signal.SIGVTALRM, self.sig_vtalrm)
         signal.setitimer(self.itimer, 0.3, 0.2)
 
-        for i in xrange(100000000):
+        start_time = time.time()
+        while time.time() - start_time < 5.0:
             # use up some virtual time by doing real work
             _ = pow(12345, 67890, 10000019)
             if signal.getitimer(self.itimer) == (0.0, 0.0):
                 break # sig_vtalrm handler stopped this itimer
+        else:
+            self.fail('timeout waiting for sig_vtalrm signal')
 
         # virtual itimer should be (0.0, 0.0) now
         self.assertEquals(signal.getitimer(self.itimer), (0.0, 0.0))
@@ -376,9 +379,14 @@
         signal.signal(signal.SIGPROF, self.sig_prof)
         signal.setitimer(self.itimer, 0.2, 0.2)
 
-        for i in xrange(100000000):
+        start_time = time.time()
+        while time.time() - start_time < 5.0:
+            # do some work
+            _ = pow(12345, 67890, 10000019)
             if signal.getitimer(self.itimer) == (0.0, 0.0):
                 break # sig_prof handler stopped this itimer
+        else:
+            self.fail('timeout waiting for sig_prof signal')
 
         # profiling itimer should be (0.0, 0.0) now
         self.assertEquals(signal.getitimer(self.itimer), (0.0, 0.0))