diff --git a/package/base-files/files/lib/functions.sh b/package/base-files/files/lib/functions.sh
index 7da0c872fa..ee4ad1af83 100755
--- a/package/base-files/files/lib/functions.sh
+++ b/package/base-files/files/lib/functions.sh
@@ -108,7 +108,7 @@ config_unset() {
 # config_get <section> <option>
 config_get() {
 	case "$2${3:-$1}" in
-		*[^A-Za-z0-9_]*) : ;;
+		*[!A-Za-z0-9_]*) : ;;
 		*)
 			case "$3" in
 				"") eval echo "\"\${CONFIG_${1}_${2}:-\${4}}\"";;