diff --git a/chameleonic.p8 b/chameleonic.p8
index 812c428..0d28ada 100644
--- a/chameleonic.p8
+++ b/chameleonic.p8
@@ -438,7 +438,7 @@ function level:spawn_exit()
   if (self:_mget(x,y)!=18) return
   for nx=x-1,x+1 do
    for ny=y-1,y+1 do
-    if nx<0 or ny<0 or nx>15 or ny>15 then
+    if (nx | ny) & 0xFFF0 ~= 0 then
      self._wins[_mix(nx,ny)]=true
     end
    end