diff --git a/wadsrc/static/shaders_gles/glsl/main.fp b/wadsrc/static/shaders_gles/glsl/main.fp
index 92e77eefe..8f8e5f855 100644
--- a/wadsrc/static/shaders_gles/glsl/main.fp
+++ b/wadsrc/static/shaders_gles/glsl/main.fp
@@ -537,7 +537,7 @@ void main()
 		#if (DEF_TEXTURE_MODE == 7)
 		{
 			float gray = grayscale(frag);
-			vec4 cm = (uObjectColor + gray * (uAddColor - uObjectColor)) * 2;
+			vec4 cm = (uObjectColor + gray * (uAddColor - uObjectColor)) * 2.0;
 			frag = vec4(clamp(cm.rgb, 0.0, 1.0), frag.a);
 		}		
 		#endif