diff --git a/shaders/glsl/mfx_lutgrading.fp b/shaders/glsl/mfx_lutgrading.fp
index 76bad30..337da7a 100644
--- a/shaders/glsl/mfx_lutgrading.fp
+++ b/shaders/glsl/mfx_lutgrading.fp
@@ -9,9 +9,9 @@ void main()
 	vec4 res = texture(InputTexture,coord);
 	vec3 lc = clamp(res.rgb,0.,63./64.);
 	vec2 lcoord = vec2((lc.r+lutindex)/32.,lc.g/64.)+vec2(1./4096.,1./8192.);
-	double minb = floor(lc.b*64.)/64.;
-	double maxb = ceil(lc.b*64.)/64.;
-	double theta = fract(lc.b*64.);
+	float minb = floor(lc.b*64.)/64.;
+	float maxb = ceil(lc.b*64.)/64.;
+	float theta = fract(lc.b*64.);
 	vec3 luta = textureLod(LUTTexture,lcoord+vec2(0,minb),0.).rgb;
 	vec3 lutb = textureLod(LUTTexture,lcoord+vec2(0,maxb),0.).rgb;
 	vec3 lutm = mix(luta,lutb,vec3(theta));	// has to be vec3 for whatever reason