diff --git a/net/mwan3/files/lib/mwan3/mwan3.sh b/net/mwan3/files/lib/mwan3/mwan3.sh
index c69f381ea8..34eec45737 100644
--- a/net/mwan3/files/lib/mwan3/mwan3.sh
+++ b/net/mwan3/files/lib/mwan3/mwan3.sh
@@ -549,7 +549,7 @@ mwan3_delete_iface_rules()
 		return
 	fi
 
-	for rule_id in $(ip rule list | awk '$1 % 1000 == '$id' && $1 > 1000 && $1 < 4000 {print substr($1,0,4)}'); do
+	for rule_id in $(ip rule list | awk 'BEGIN {FS=":"} $1 % 1000 == '$id' && $1 > 1000 && $1 < 4000 {print $1}'); do
 		$IP rule del pref $rule_id
 	done
 }