diff --git a/crt/shaders/zfast_crt/zfast_crt_coarsemask.slang b/crt/shaders/zfast_crt/zfast_crt_coarsemask.slang
new file mode 100644
index 0000000..612aa06
--- /dev/null
+++ b/crt/shaders/zfast_crt/zfast_crt_coarsemask.slang
@@ -0,0 +1,3 @@
+#version 450
+
+#include "zfast_crt_impl.inc"
diff --git a/crt/shaders/zfast_crt/zfast_crt_finemask.slang b/crt/shaders/zfast_crt/zfast_crt_finemask.slang
new file mode 100644
index 0000000..7241cc0
--- /dev/null
+++ b/crt/shaders/zfast_crt/zfast_crt_finemask.slang
@@ -0,0 +1,8 @@
+#version 450
+
+// This can't be an option without slowing the shader down.
+// Note that only the fine mask works on SNES Classic Edition
+// due to Mali 400 gpu precision.
+#define FINEMASK
+
+#include "zfast_crt_impl.inc"
diff --git a/crt/shaders/zfast_crt.slang b/crt/shaders/zfast_crt/zfast_crt_impl.inc
similarity index 94%
rename from crt/shaders/zfast_crt.slang
rename to crt/shaders/zfast_crt/zfast_crt_impl.inc
index 4b922ce..66131b4 100644
--- a/crt/shaders/zfast_crt.slang
+++ b/crt/shaders/zfast_crt/zfast_crt_impl.inc
@@ -1,5 +1,3 @@
-#version 450
-
 /*
     zfast_crt_standard - A simple, fast CRT shader.
 
@@ -52,10 +50,6 @@ layout(std140, set = 0, binding = 0) uniform UBO
 //#define FRAGMENT
 //#define VERTEX
 
-//This can't be an option without slowing the shader down
-//Comment this out for a coarser 3 pixel mask...which is currently broken
-//on SNES Classic Edition due to Mali 400 gpu precision
-#define FINEMASK
 //Some drivers don't return black with texture coordinates out of bounds
 //SNES Classic is too slow to black these areas out when using fullscreen
 //overlays.  But you can uncomment the below to black them out if necessary
@@ -98,7 +92,7 @@ void main()
 	float whichmask = fract(floor(vTexCoord.x*params.OutputSize.x*-0.4999));
 	float mask = 1.0 + float(whichmask < 0.5) * -MASK_DARK;
 #else
-	float whichmask = fract(floor(vTexCoord.x*params.OutputSize.x)*-0.3333));
+	float whichmask = fract(floor(vTexCoord.x*params.OutputSize.x)*-0.3333);
 	float mask = 1.0 + float(whichmask <= 0.33333) * -MASK_DARK;
 #endif
 	vec3 colour = texture(Source, p).rgb;
diff --git a/crt/zfast-crt-hdmask.slangp b/crt/zfast-crt-hdmask.slangp
new file mode 100644
index 0000000..acbc181
--- /dev/null
+++ b/crt/zfast-crt-hdmask.slangp
@@ -0,0 +1,4 @@
+shaders = 1
+
+shader0 = shaders/zfast_crt/zfast_crt_coarsemask.slang
+filter_linear0 = true
diff --git a/crt/zfast-crt.slangp b/crt/zfast-crt.slangp
index dd4afc3..e428734 100644
--- a/crt/zfast-crt.slangp
+++ b/crt/zfast-crt.slangp
@@ -1,4 +1,4 @@
 shaders = 1
 
-shader0 = shaders/zfast_crt.slang
+shader0 = shaders/zfast_crt/zfast_crt_finemask.slang
 filter_linear0 = true
\ No newline at end of file