diff --git a/contrib/showstack.py b/contrib/showstack.py
--- a/contrib/showstack.py
+++ b/contrib/showstack.py
@@ -4,7 +4,7 @@
 """dump stack trace when receiving SIGQUIT (Ctrl-\) and SIGINFO (Ctrl-T on BSDs)
 """
 
-from __future__ import absolute_import
+from __future__ import absolute_import, print_function
 import signal
 import sys
 import traceback
@@ -14,8 +14,14 @@
     traceback.print_stack(args[1], limit=10, file=sys.stderr)
     sys.stderr.write("----\n")
 
+def sigexit(*args):
+    sigshow(*args)
+    print('alarm!')
+    sys.exit(1)
+
 def extsetup(ui):
     signal.signal(signal.SIGQUIT, sigshow)
+    signal.signal(signal.SIGALRM, sigexit)
     try:
         signal.signal(signal.SIGINFO, sigshow)
     except AttributeError: