diff --git a/misc/alpine-install.func b/misc/alpine-install.func
index 29e4e8a..885e7f3 100644
--- a/misc/alpine-install.func
+++ b/misc/alpine-install.func
@@ -195,7 +195,7 @@ customize() {
   echo "bash -c \"\$(curl -fsSL https://github.com/community-scripts/ProxmoxVED/raw/main/ct/${app}.sh)\"" >/usr/bin/update
   chmod +x /usr/bin/update
 
-  NS_VALUE=$(echo "$PCT_OPTIONS" | grep -oP '(?<=-nameserver=)[^\s]+')
+  NS_VALUE=$(echo "$PCT_OPTIONS" | sed -n 's/.*-nameserver=\([^ ]*\).*/\1/p')
 
   if [ "$NS_VALUE" != "" ] && [ "$NS_VALUE" != "Host" ]; then