diff --git a/anti-aliasing/shaders/smaa/SMAA.hlsl b/anti-aliasing/shaders/smaa/SMAA.hlsl
index 2c8d497..5b807fe 100644
--- a/anti-aliasing/shaders/smaa/SMAA.hlsl
+++ b/anti-aliasing/shaders/smaa/SMAA.hlsl
@@ -792,11 +792,11 @@ float2 SMAAColorEdgeDetectionPS(float2 texcoord,
 
     // Calculate left-left and top-top deltas:
     float3 Cleftleft  = SMAASamplePoint(colorTex, offset[2].xy).rgb;
-    t = abs(C - Cleftleft);
+    t = abs(Cleft - Cleftleft);
     delta.z = max(max(t.r, t.g), t.b);
 
     float3 Ctoptop = SMAASamplePoint(colorTex, offset[2].zw).rgb;
-    t = abs(C - Ctoptop);
+    t = abs(Ctop - Ctoptop);
     delta.w = max(max(t.r, t.g), t.b);
 
     // Calculate the final maximum delta: