diff --git a/Shorewall-perl/Shorewall/Rules.pm b/Shorewall-perl/Shorewall/Rules.pm
index e86c35b72..89d7e20eb 100644
--- a/Shorewall-perl/Shorewall/Rules.pm
+++ b/Shorewall-perl/Shorewall/Rules.pm
@@ -74,7 +74,7 @@ sub initialize() {
     $sectioned = 0;
     $macro_nest_level = 0;
     $current_param = '';
-    @param_stack;
+    @param_stack = ();
 }
 
 INIT {