diff --git a/acme.sh b/acme.sh
index 3c08fd5a..625cff12 100755
--- a/acme.sh
+++ b/acme.sh
@@ -4203,7 +4203,7 @@ _process() {
           fi
           
           _sepexis=$(echo $_dvalue | grep ",")
-          if [ $_sepexis ]; then
+          if [ "$_sepexis" ]; then
             _err "'$_dvalue' is not a valid domain for parameter '$1', please use more command to add domains"
             return 1
           fi