diff --git a/python/mach/mach/main.py b/python/mach/mach/main.py
index 2094511a06cf..75aed4650e9e 100644
--- a/python/mach/mach/main.py
+++ b/python/mach/mach/main.py
@@ -303,7 +303,7 @@ To see more help for a specific command, run:
             if not result:
                 result = 0
 
-            assert isinstance(result, int)
+            assert isinstance(result, (int, long))
 
             return result
         except KeyboardInterrupt as ki: