diff --git a/ext/cog/cog.orc b/ext/cog/cog.orc
index dabb192b3f..052c4a1097 100644
--- a/ext/cog/cog.orc
+++ b/ext/cog/cog.orc
@@ -270,8 +270,6 @@ convsuswb d1, t1
 .source 1 s2 uint8_t
 .param 2 p1
 .param 2 p2
-.param 2 p3
-.param 2 p4
 .temp 2 t1
 .temp 2 t2
 .temp 2 t3
@@ -284,8 +282,8 @@ convubw t2, s2
 subw t2, t2, 128
 mullw t4, t2, p2
 addw t3, t3, t4
-addw t3, t3, p3
-shrsw t3, t3, p4
+addw t3, t3, 128
+shrsw t3, t3, 8
 addw t3, t3, t1
 addw t3, t3, t2
 convsuswb d1, t3
@@ -297,8 +295,6 @@ convsuswb d1, t3
 .source 1 s2 uint8_t
 .param 2 p1
 .param 2 p2
-.param 2 p3
-.param 2 p4
 .temp 2 t1
 .temp 2 t2
 .temp 2 t3
@@ -311,8 +307,8 @@ convubw t2, s2
 subw t2, t2, 128
 mullw t4, t2, p2
 addw t3, t3, t4
-addw t3, t3, p3
-shrsw t3, t3, p4
+addw t3, t3, 128
+shrsw t3, t3, 8
 addw t3, t3, t1
 addw t3, t3, t2
 addw t3, t3, t2
@@ -352,8 +348,6 @@ convsuswb d1, t1
 .param 2 p1
 .param 2 p2
 .param 2 p3
-.param 2 p4
-.param 2 p5
 .temp 2 t1
 .temp 2 t2
 .temp 2 t3
@@ -370,8 +364,8 @@ convubw t2, s3
 subw t2, t2, 128
 mullw t2, t2, p3
 addw t3, t3, t2
-addw t3, t3, p4
-shrsw t3, t3, p5
+addw t3, t3, 128
+shrsw t3, t3, 8
 addw t3, t3, t1
 convsuswb d1, t3
 
diff --git a/ext/cog/cogvirtframe.c b/ext/cog/cogvirtframe.c
index 836b1af946..718c91ba84 100644
--- a/ext/cog/cogvirtframe.c
+++ b/ext/cog/cogvirtframe.c
@@ -1408,16 +1408,14 @@ color_matrix_YCbCr_to_RGB_8bit (CogFrame * frame, void *_dest, int component,
 
   switch (component) {
     case 0:
-      orc_matrix2_11_u8 (dest, src1, src3,
-          matrix[0], matrix[2], 128, 8, frame->width);
+      orc_matrix2_11_u8 (dest, src1, src3, matrix[0], matrix[2], frame->width);
       break;
     case 1:
       orc_matrix3_100_u8 (dest, src1, src2, src3,
-          matrix[4], matrix[5], matrix[6], 128, 8, frame->width);
+          matrix[4], matrix[5], matrix[6], frame->width);
       break;
     case 2:
-      orc_matrix2_12_u8 (dest, src1, src2,
-          matrix[8], matrix[9], 128, 8, frame->width);
+      orc_matrix2_12_u8 (dest, src1, src2, matrix[8], matrix[9], frame->width);
       break;
     default:
       break;