diff --git a/Source/Engine/UI/GUI/WindowRootControl.cs b/Source/Engine/UI/GUI/WindowRootControl.cs
index f39cf0346..29d252ed1 100644
--- a/Source/Engine/UI/GUI/WindowRootControl.cs
+++ b/Source/Engine/UI/GUI/WindowRootControl.cs
@@ -274,7 +274,7 @@ namespace FlaxEngine.GUI
             if (_focusedControl != null)
             {
                 _focusedControl.OnGotFocus();
-                Assert.IsTrue(_focusedControl.IsFocused);
+                Assert.IsTrue(_focusedControl == null || _focusedControl.IsFocused);
             }
 
             // Update flags