diff --git a/app.js b/app.js
index 01b9c20..f85d6a0 100644
--- a/app.js
+++ b/app.js
@@ -224,10 +224,10 @@ app.post("/api/building/:id/upgrade", requireLogin, async (req, res) => {
       [levelData.wood, levelData.stone, levelData.gold, userId],
     );
 
-    // Level erhöhen, Punkte zurücksetzen
+    // Level erhöhen, nur benötigte Punkte abziehen
     await db.query(
-      "UPDATE user_buildings SET level = ?, points = 0 WHERE id = ?",
-      [nextLevel, userBuilding.id],
+      "UPDATE user_buildings SET level = ?, points = points - ? WHERE id = ?",
+      [nextLevel, levelData.required_points, userBuilding.id],
     );
 
     res.json({