diff --git a/package/base-files/files/etc/functions.sh b/package/base-files/files/etc/functions.sh
index efa378f006..eb7faac1fe 100755
--- a/package/base-files/files/etc/functions.sh
+++ b/package/base-files/files/etc/functions.sh
@@ -91,8 +91,8 @@ list() {
 	local value="$*"
 	local len
 
-	config_get len "$CONFIG_SECTION" "${varname}_LENGTH" 
-	len="$((${len:-0} + 1))"
+	config_get len "$CONFIG_SECTION" "${varname}_LENGTH" 0
+	len=$(($len + 1))
 	config_set "$CONFIG_SECTION" "${varname}_ITEM$len" "$value"
 	config_set "$CONFIG_SECTION" "${varname}_LENGTH" "$len"
 	append "CONFIG_${CONFIG_SECTION}_${varname}" "$value" "$LIST_SEP"