diff --git a/misc/build.func b/misc/build.func
index c02fb20d..99eec438 100644
--- a/misc/build.func
+++ b/misc/build.func
@@ -733,7 +733,8 @@ config_file(){
     exit
   fi
 
-  if [[ ! -z "$CT_ID" ]]; then
+  if [[ -n "$CT_ID" ]]; then
+
     if [[ "$CT_ID" =~ ^([0-9]{3,4})-([0-9]{3,4})$ ]]; then
       MIN_ID=${BASH_REMATCH[1]}
       MAX_ID=${BASH_REMATCH[2]}