diff --git a/src/module/Application/pwa/js/WordRotatorDb.js b/src/module/Application/pwa/js/WordRotatorDb.js
index 1bd1367..04fe4c2 100755
--- a/src/module/Application/pwa/js/WordRotatorDb.js
+++ b/src/module/Application/pwa/js/WordRotatorDb.js
@@ -11,7 +11,7 @@ export class WordRotatorDb extends MyDb {
     }
 
     constructor() {
-        super("wordRotator", 4);
+        super("wordRotator", 5);
     }
 
     upgrade(db, oldVersion, newVersion, e) {
@@ -30,8 +30,10 @@ export class WordRotatorDb extends MyDb {
             levelObjectStore.createIndex("difficulty", "difficulty", {"unique": false});
         }
 
-        if (Helper.isNull(oldVersion) || oldVersion < 3 && newVersion >= 4) {
-            let levelObjectStore = db.createObjectStore(WordRotatorDb.OBJECT_STORE.SYSTEM_VARS, {"keyPath": "name"});
+        if (Helper.isNull(oldVersion) || oldVersion < 5 && newVersion >= 5) {
+            if (!e.target.transaction.objectStore(WordRotatorDb.OBJECT_STORE.LEVEL)){
+                let levelObjectStore = db.createObjectStore(WordRotatorDb.OBJECT_STORE.SYSTEM_VARS, {"keyPath": "name"});
+            }
         }
     };