diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
index f5daa67431..495e46bf52 100644
--- a/libavcodec/vc1_block.c
+++ b/libavcodec/vc1_block.c
@@ -99,12 +99,14 @@ static void vc1_put_signed_blocks_clamped(VC1Context *v)
             s->idsp.put_signed_pixels_clamped(v->block[v->topleft_blk_idx][3],
                                               s->dest[0] - v_dist * s->linesize - 8,
                                               stride_y);
+            if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY)) {
             s->idsp.put_signed_pixels_clamped(v->block[v->topleft_blk_idx][4],
                                               s->dest[1] - 8 * s->uvlinesize - 8,
                                               s->uvlinesize);
             s->idsp.put_signed_pixels_clamped(v->block[v->topleft_blk_idx][5],
                                               s->dest[2] - 8 * s->uvlinesize - 8,
                                               s->uvlinesize);
+            }
         }
         if (s->mb_x == s->mb_width - 1) {
             top_mb_pos = (s->mb_y - 1) * s->mb_stride + s->mb_x;
@@ -124,12 +126,14 @@ static void vc1_put_signed_blocks_clamped(VC1Context *v)
             s->idsp.put_signed_pixels_clamped(v->block[v->top_blk_idx][3],
                                               s->dest[0] - v_dist * s->linesize + 8,
                                               stride_y);
+            if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY)) {
             s->idsp.put_signed_pixels_clamped(v->block[v->top_blk_idx][4],
                                               s->dest[1] - 8 * s->uvlinesize,
                                               s->uvlinesize);
             s->idsp.put_signed_pixels_clamped(v->block[v->top_blk_idx][5],
                                               s->dest[2] - 8 * s->uvlinesize,
                                               s->uvlinesize);
+            }
         }
     }
 
diff --git a/libavcodec/vc1_loopfilter.c b/libavcodec/vc1_loopfilter.c
index 95c4519809..1a7037fcb2 100644
--- a/libavcodec/vc1_loopfilter.c
+++ b/libavcodec/vc1_loopfilter.c
@@ -40,6 +40,7 @@ void ff_vc1_loop_filter_iblk(VC1Context *v, int pq)
         if (s->mb_x)
             v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 16 * s->linesize, s->linesize, pq);
         v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 16 * s->linesize + 8, s->linesize, pq);
+        if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY))
         for (j = 0; j < 2; j++) {
             v->vc1dsp.vc1_v_loop_filter8(s->dest[j + 1], s->uvlinesize, pq);
             if (s->mb_x)
@@ -51,8 +52,10 @@ void ff_vc1_loop_filter_iblk(VC1Context *v, int pq)
     if (s->mb_y == s->end_mb_y - 1) {
         if (s->mb_x) {
             v->vc1dsp.vc1_h_loop_filter16(s->dest[0], s->linesize, pq);
+            if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY)) {
             v->vc1dsp.vc1_h_loop_filter8(s->dest[1], s->uvlinesize, pq);
             v->vc1dsp.vc1_h_loop_filter8(s->dest[2], s->uvlinesize, pq);
+            }
         }
         v->vc1dsp.vc1_h_loop_filter16(s->dest[0] + 8, s->linesize, pq);
     }
@@ -73,6 +76,7 @@ void ff_vc1_loop_filter_iblk_delayed(VC1Context *v, int pq)
                 if (s->mb_x >= 2)
                     v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 32 * s->linesize - 16, s->linesize, pq);
                 v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 32 * s->linesize - 8, s->linesize, pq);
+                if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY))
                 for (j = 0; j < 2; j++) {
                     v->vc1dsp.vc1_v_loop_filter8(s->dest[j + 1] - 8 * s->uvlinesize - 8, s->uvlinesize, pq);
                     if (s->mb_x >= 2) {
@@ -90,6 +94,7 @@ void ff_vc1_loop_filter_iblk_delayed(VC1Context *v, int pq)
                 if (s->mb_x)
                     v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 32 * s->linesize, s->linesize, pq);
                 v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 32 * s->linesize + 8, s->linesize, pq);
+                if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY))
                 for (j = 0; j < 2; j++) {
                     v->vc1dsp.vc1_v_loop_filter8(s->dest[j + 1] - 8 * s->uvlinesize, s->uvlinesize, pq);
                     if (s->mb_x >= 2) {
@@ -105,7 +110,7 @@ void ff_vc1_loop_filter_iblk_delayed(VC1Context *v, int pq)
                 if (s->mb_x >= 2)
                     v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 16 * s->linesize - 16, s->linesize, pq);
                 v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 16 * s->linesize - 8, s->linesize, pq);
-                if (s->mb_x >= 2) {
+                if (s->mb_x >= 2 && !(s->flags & CODEC_FLAG_GRAY)) {
                     for (j = 0; j < 2; j++) {
                         v->vc1dsp.vc1_h_loop_filter8(s->dest[j + 1] - 8 * s->uvlinesize - 8, s->uvlinesize, pq);
                     }
@@ -116,7 +121,7 @@ void ff_vc1_loop_filter_iblk_delayed(VC1Context *v, int pq)
                 if (s->mb_x)
                     v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 16 * s->linesize, s->linesize, pq);
                 v->vc1dsp.vc1_h_loop_filter16(s->dest[0] - 16 * s->linesize + 8, s->linesize, pq);
-                if (s->mb_x) {
+                if (s->mb_x && !(s->flags & CODEC_FLAG_GRAY)) {
                     for (j = 0; j < 2; j++) {
                         v->vc1dsp.vc1_h_loop_filter8(s->dest[j + 1] - 8 * s->uvlinesize, s->uvlinesize, pq);
                     }
@@ -150,7 +155,7 @@ void ff_vc1_smooth_overlap_filter_iblk(VC1Context *v)
                                       v->block[v->cur_blk_idx][0]);
             v->vc1dsp.vc1_h_s_overlap(v->block[v->left_blk_idx][3],
                                       v->block[v->cur_blk_idx][2]);
-            if (!(s->flags & CODEC_FLAG_GRAY)) {
+            if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY)) {
                 v->vc1dsp.vc1_h_s_overlap(v->block[v->left_blk_idx][4],
                                           v->block[v->cur_blk_idx][4]);
                 v->vc1dsp.vc1_h_s_overlap(v->block[v->left_blk_idx][5],
@@ -169,7 +174,7 @@ void ff_vc1_smooth_overlap_filter_iblk(VC1Context *v)
                                           v->block[v->cur_blk_idx][0]);
                 v->vc1dsp.vc1_v_s_overlap(v->block[v->top_blk_idx][3],
                                           v->block[v->cur_blk_idx][1]);
-                if (!(s->flags & CODEC_FLAG_GRAY)) {
+                if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY)) {
                     v->vc1dsp.vc1_v_s_overlap(v->block[v->top_blk_idx][4],
                                               v->block[v->cur_blk_idx][4]);
                     v->vc1dsp.vc1_v_s_overlap(v->block[v->top_blk_idx][5],
@@ -189,7 +194,7 @@ void ff_vc1_smooth_overlap_filter_iblk(VC1Context *v)
                                       v->block[v->left_blk_idx][0]);
             v->vc1dsp.vc1_v_s_overlap(v->block[v->topleft_blk_idx][3],
                                       v->block[v->left_blk_idx][1]);
-            if (!(s->flags & CODEC_FLAG_GRAY)) {
+            if (!CONFIG_GRAY || !(s->flags & CODEC_FLAG_GRAY)) {
                 v->vc1dsp.vc1_v_s_overlap(v->block[v->topleft_blk_idx][4],
                                           v->block[v->left_blk_idx][4]);
                 v->vc1dsp.vc1_v_s_overlap(v->block[v->topleft_blk_idx][5],
@@ -331,21 +336,22 @@ void ff_vc1_apply_p_loop_filter(VC1Context *v)
 {
     MpegEncContext *s = &v->s;
     int i;
+    int block_count = CONFIG_GRAY && (s->flags & CODEC_FLAG_GRAY) ? 4 : 6;
 
-    for (i = 0; i < 6; i++) {
+    for (i = 0; i < block_count; i++) {
         vc1_apply_p_v_loop_filter(v, i);
     }
 
     /* V always precedes H, therefore we run H one MB before V;
      * at the end of a row, we catch up to complete the row */
     if (s->mb_x) {
-        for (i = 0; i < 6; i++) {
+        for (i = 0; i < block_count; i++) {
             vc1_apply_p_h_loop_filter(v, i);
         }
         if (s->mb_x == s->mb_width - 1) {
             s->mb_x++;
             ff_update_block_index(s);
-            for (i = 0; i < 6; i++) {
+            for (i = 0; i < block_count; i++) {
                 vc1_apply_p_h_loop_filter(v, i);
             }
         }