diff --git a/Unity-Package/Assets/root/Runtime/Future/Types/FutureSprite.cs b/Unity-Package/Assets/root/Runtime/Future/Types/FutureSprite.cs
index f702354..c058ddf 100644
--- a/Unity-Package/Assets/root/Runtime/Future/Types/FutureSprite.cs
+++ b/Unity-Package/Assets/root/Runtime/Future/Types/FutureSprite.cs
@@ -87,8 +87,8 @@ public static void ReleaseMemorySprite(Sprite sprite, DebugLevel logLevel = Debu
             }
 
             // 'sprite.texture' could be called only from main thread
-            // checking sprite.IsNull is enough until we are in main thread
-            if (sprite.IsNull())
+            // Unity's == (used by IsNull) throws off the main thread, e.g. from a Reference finalizer
+            if (ReferenceEquals(sprite, null))
                 return;
 
             UniTask.Post(() =>
diff --git a/Unity-Package/Assets/root/Runtime/Future/Types/FutureTexture.cs b/Unity-Package/Assets/root/Runtime/Future/Types/FutureTexture.cs
index 72d843b..bd97028 100644
--- a/Unity-Package/Assets/root/Runtime/Future/Types/FutureTexture.cs
+++ b/Unity-Package/Assets/root/Runtime/Future/Types/FutureTexture.cs
@@ -46,7 +46,8 @@ public static void ReleaseMemoryTexture(Texture2D obj, DebugLevel logLevel = Deb
                 UnityEngine.Object.DestroyImmediate(obj);
                 return;
             }
-            if (obj.IsNull())
+            // Unity's == (used by IsNull) throws off the main thread, e.g. from a Reference finalizer
+            if (ReferenceEquals(obj, null))
                 return;
 
             UniTask.Post(() =>