diff --git a/luci-app-mosdns/root/usr/share/mosdns/mosdns.sh b/luci-app-mosdns/root/usr/share/mosdns/mosdns.sh
index 22d1af2..eca1a11 100755
--- a/luci-app-mosdns/root/usr/share/mosdns/mosdns.sh
+++ b/luci-app-mosdns/root/usr/share/mosdns/mosdns.sh
@@ -39,9 +39,9 @@ ad_block() (
 
 adlist_update() (
 	ad_source=$(uci -q get mosdns.config.ad_source)
-	[ "$ad_source" = "geosite.dat" ] && exit 0
+	[ "$ad_source" = "geosite.dat" ] || [ -z "$ad_source" ] && exit 0
 	AD_TMPDIR=$(mktemp -d) || exit 1
-	if [[ "$ad_source" =~ "^https://raw.githubusercontent.com" ]]; then
+	if echo "$ad_source" | grep -Eq "^https://raw.githubusercontent.com" ; then
 		google_status=$(curl -I -4 -m 3 -o /dev/null -s -w %{http_code} http://www.google.com/generate_204)
 		[ "$google_status" -ne "204" ] && mirror="https://ghproxy.com/"
 	fi