diff --git a/tools/test.py b/tools/test.py
index b511004a73..42f25ae522 100755
--- a/tools/test.py
+++ b/tools/test.py
@@ -1414,7 +1414,7 @@ def BuildOptions():
       default=1, type="int")
   result.add_option('--abort-on-timeout',
       help='Send SIGABRT instead of SIGTERM to kill processes that time out',
-      default=False, dest="abort_on_timeout")
+      default=False, action="store_true", dest="abort_on_timeout")
   return result