diff --git a/src/cache.h b/src/cache.h
index 438eb80..cd832bb 100644
--- a/src/cache.h
+++ b/src/cache.h
@@ -76,6 +76,7 @@ struct ShaderCache {
         compile(Core::passAmbient, Shader::ROOM,   fx | FX_UNDERWATER, rsFull | RS_DISCARD);
         compile(Core::passAmbient, Shader::SPRITE, fx,                 rsFull | RS_DISCARD);
         compile(Core::passAmbient, Shader::SPRITE, fx | FX_UNDERWATER, rsFull | RS_DISCARD);
+        compile(Core::passAmbient, Shader::FLASH,  fx,                 rsFull); // sky
     }
 
     void prepareShadows(int fx) {