diff --git a/sbin/vol-backup b/sbin/vol-backup
index abf9cef..52b50a7 100755
--- a/sbin/vol-backup
+++ b/sbin/vol-backup
@@ -27,7 +27,7 @@ if [ -d "volumes" ]; then
 
   # Compress all volumes excerpt mysql and postgres
   BACKUP=${PWD##*/}.tar.zst
-  tar --zstd -cf --exclude={"mysql", "postgres"} /tmp/$BACKUP -C volumes .
+  tar --zstd -cf --exclude='mysql' --exclude='postgres' /tmp/$BACKUP -C volumes .
 
   # Put it into the storage box (pubkey needed)
   STORAGE_BOX=u442569@u442569.your-storagebox.de