diff --git a/cert/vpsRenew b/cert/vpsRenew
index b2f68a2..86eb0a9 100755
--- a/cert/vpsRenew
+++ b/cert/vpsRenew
@@ -5,7 +5,7 @@ T=$SDIR/../step
 ACME_FILE=$1
 ACME_VALUE=$2
 
-if [ -z "$FILE" ] || [ -z "$VALUE" ]; then
+if [ -z "$ACME_FILE" ] || [ -z "$ACME_VALUE" ]; then
   echo "Usage: $0 ACME_FILE ACME_VALUE"
   exit 1
 fi