diff --git a/tools/test/stress2/misc/ifconfig.sh b/tools/test/stress2/misc/ifconfig.sh
index 6359711a044..7b3c7e317ec 100755
--- a/tools/test/stress2/misc/ifconfig.sh
+++ b/tools/test/stress2/misc/ifconfig.sh
@@ -50,7 +50,7 @@ start=`date +%s`
 while [ $((`date +%s` - start)) -lt 300 ]; do
 	for i in `jot 255`; do
 		(ifconfig $if.$i create
-		ifconfig $if.$i inet 224.0.0.$i
+		ifconfig $if.$i inet 224.0.0.$i netmask 255.255.255.0
 		ifconfig $if.$i destroy) > /dev/null 2>&1 &
 	done
 	wait
diff --git a/tools/test/stress2/misc/ifconfig2.sh b/tools/test/stress2/misc/ifconfig2.sh
index 61abbab3dd5..273db43a329 100755
--- a/tools/test/stress2/misc/ifconfig2.sh
+++ b/tools/test/stress2/misc/ifconfig2.sh
@@ -53,7 +53,7 @@ for i in `jot 5`; do
 		done
 		while [ -f $sync ]; do
 			ifconfig $if.$i create
-			ifconfig $if.$i inet 224.0.0.$i
+			ifconfig $if.$i inet 224.0.0.$i netmask 255.255.255.0
 			ifconfig $if.$i destroy
 		done
 	) > /dev/null 2>&1 &