diff --git a/ucloud-init.start b/ucloud-init.start
index ac3e683..54f2241 100755
--- a/ucloud-init.start
+++ b/ucloud-init.start
@@ -71,7 +71,7 @@ setup_dns() {
 
 	# Check if rdnssd is installed, if not put Google's DNS
 	# into /etc/resolv.conf and install rdnssd for the next time
-	if ! $(which rdnssd); then
+	if ! which rdnssd; then
 		echo "nameserver 2001:4860:4860::8888" >> $etc_resolv_path
 		echo "nameserver 2001:4860:4860::8844" >> $etc_resolv_path
 		echo "nameserver 8.8.8.8" >> $etc_resolv_path