diff --git a/src/engine/gameManager/BuildingManager.java b/src/engine/gameManager/BuildingManager.java
index 271179a2..90c4cef3 100644
--- a/src/engine/gameManager/BuildingManager.java
+++ b/src/engine/gameManager/BuildingManager.java
@@ -25,6 +25,7 @@ import engine.objects.*;
 import engine.server.MBServerStatics;
 import org.pmw.tinylog.Logger;
 
+import java.time.Instant;
 import java.time.LocalDateTime;
 import java.time.ZoneId;
 import java.util.ArrayList;
@@ -274,7 +275,8 @@ public enum BuildingManager {
 
         if (building == null)
             return;
-        if (!DbManager.BuildingQueries.updateBuildingUpgradeTime(upgradeDateTime.atZone(ZoneId.systemDefault()).toInstant(), building, rankCost)) {
+        Instant instant = (upgradeDateTime == null) ? null : upgradeDateTime.atZone(ZoneId.systemDefault()).toInstant();
+        if (!DbManager.BuildingQueries.updateBuildingUpgradeTime(instant, building, rankCost)) {
             Logger.error("Failed to set upgradeTime for building " + building.getObjectUUID());
             return;
         }