diff --git a/Photorealistic-Rendering-Engine-based-on-Unreal-Engine.md b/Photorealistic-Rendering-Engine-based-on-Unreal-Engine.md
index 054de96..ffcea0b 100644
--- a/Photorealistic-Rendering-Engine-based-on-Unreal-Engine.md
+++ b/Photorealistic-Rendering-Engine-based-on-Unreal-Engine.md
@@ -9,6 +9,8 @@ Before running the simulator, you need to launch the UnrealCV server as follows:
     cd <path_to_the_unrealcv_server_code>
     ./LinuxNoEditor/playground.sh
 
+Please make sure that the mouse input is disabled in the window that will pop up, by hitting the ` key while the window is in focus.
+
 ## Run
 
 Once an UnrealCV server is running, you can run the simulator as follows: