diff --git a/Source/Engine/Serialization/JsonSerializer.cs b/Source/Engine/Serialization/JsonSerializer.cs
index c634f9eaa..de1556577 100644
--- a/Source/Engine/Serialization/JsonSerializer.cs
+++ b/Source/Engine/Serialization/JsonSerializer.cs
@@ -265,7 +265,7 @@ namespace FlaxEngine.Json
             
             // Special case when saving reference to prefab object and the objects are different but the point to the same prefab object
             // In that case, skip saving reference as it's defined in prefab (will be populated via IdsMapping during deserialization)
-            if (objA is SceneObject sceneA && objB is SceneObject sceneB && sceneA.HasPrefabLink && sceneB.HasPrefabLink)
+            if (objA is SceneObject sceneA && objB is SceneObject sceneB && sceneA && sceneB && sceneA.HasPrefabLink && sceneB.HasPrefabLink)
                 return sceneA.PrefabObjectID == sceneB.PrefabObjectID;
 
             // Comparing an Int32 and Int64 both of the same value returns false, make types the same then compare