diff --git a/wadsrc/static/shaders/glsl/present.fp b/wadsrc/static/shaders/glsl/present.fp
index eff874ed2..4690895c2 100644
--- a/wadsrc/static/shaders/glsl/present.fp
+++ b/wadsrc/static/shaders/glsl/present.fp
@@ -12,13 +12,10 @@ uniform int GrayFormula;
 vec4 ApplyGamma(vec4 c)
 {
 	vec3 valgray;
-	if (Saturation != 1.0) // attempt to cool things a bit, this calculation makes the GPU run really hot
-		if (GrayFormula == 0)
-			valgray = vec3(c.r + c.g + c.b) * (1 - Saturation) / 3 + c.rgb * Saturation;
-		else
-			valgray = vec3(0.3 * c.r + 0.56 * c.g + 0.14 * c.b) * (1 - Saturation) + c.rgb * Saturation;
+	if (GrayFormula == 0)
+		valgray = vec3(c.r + c.g + c.b) * (1 - Saturation) / 3 + c.rgb * Saturation;
 	else
-		valgray = c.rgb;
+		valgray = mix(vec3(dot(c.rgb, vec3(0.3,0.56,0.14))), c.rgb, Saturation);
 	vec3 val = valgray * Contrast - (Contrast - 1.0) * 0.5;
 	val += Brightness * 0.5;
 	val = pow(max(val, vec3(0.0)), vec3(InvGamma));