diff --git a/src/cache.h b/src/cache.h
index a133f19..e28df67 100644
--- a/src/cache.h
+++ b/src/cache.h
@@ -497,7 +497,11 @@ struct WaterCache {
                         int xt = int(r.info.x + x * 1024 - rt.info.x) / 1024;
                         int zt = int(r.info.z + z * 1024 - rt.info.z) / 1024;
                         TR::Room::Sector &st = rt.sectors[xt * rt.zSectors + zt];
-                        hasWater = s.ceiling > st.ceiling; // TODO fix for LEVEL10A, use slant
+                        hasWater = s.ceiling > st.ceiling;
+                        if (s.ceiling == st.ceiling) {
+                            vec3 p = vec3(float(r.info.x + x * 1024 + 512), float(posY), float(r.info.z + z * 1024 + 512));
+                            hasWater = (s.ceiling * 256 - level->getCeiling(&s, p)) > 8.0f;
+                        }
                     }
 
                     m[(x - minX) + w * (z - minZ)] = hasWater ? 0xF800 : 0;
diff --git a/src/shaders/filter.glsl b/src/shaders/filter.glsl
index c0a3ab5..b648846 100644
--- a/src/shaders/filter.glsl
+++ b/src/shaders/filter.glsl
@@ -39,7 +39,7 @@ uniform vec4 uParam;
 	vec4 grayscale() { // uParam (factor, unused, unused, unused)
 		vec4 color = texture2D(sDiffuse, vTexCoord);
 		vec3 gray  = vec3(dot(color, vec4(0.299, 0.587, 0.114, 0.0)));
-		return vec4(mix(color.xyz, gray, uParam.x), color.w);
+		return vec4(mix(color.xyz, gray, uParam.w) * uParam.xyz, color.w);
 	}
 
 	vec4 blur() { // uParam (dirX, dirY, 1 / textureSize, unused)