diff --git a/ascii.cpp b/ascii.cpp
index 05d3ecd..6abb0b9 100644
--- a/ascii.cpp
+++ b/ascii.cpp
@@ -229,9 +229,12 @@ int main(int argc,char*argv[]) {
             }
         }
         keys = SDL_GetKeyboardState(NULL);
-        mouse_buttons = SDL_GetMouseState(&mouse_x, &mouse_y);
-        mouse_x = (mouse_x-40) / (640/screen_width);
-        mouse_y = (mouse_y-40) / (480/screen_height);
+        int mx, my;
+        mouse_buttons = SDL_GetMouseState(&mx, &my);
+        if (mx>=40 && my>=40 && mx<680 && my<520) {
+            mouse_x = (mx-40) / (640/screen_width);
+            mouse_y = (my-40) / (480/screen_height);
+        }
         
         if (lua_is_playing()) {
             lua_call_update();