diff --git a/av1/encoder/firstpass.c b/av1/encoder/firstpass.c
index 7ad0c8d..7e137d0 100644
--- a/av1/encoder/firstpass.c
+++ b/av1/encoder/firstpass.c
@@ -473,8 +473,10 @@
 
   set_mi_offsets(mi_params, xd, unit_row * unit_scale, unit_col * unit_scale);
   xd->plane[0].dst.buf = this_frame->y_buffer + y_offset;
-  xd->plane[1].dst.buf = this_frame->u_buffer + uv_offset;
-  xd->plane[2].dst.buf = this_frame->v_buffer + uv_offset;
+  if (num_planes > 1) {
+    xd->plane[1].dst.buf = this_frame->u_buffer + uv_offset;
+    xd->plane[2].dst.buf = this_frame->v_buffer + uv_offset;
+  }
   xd->left_available = (unit_col != 0);
   xd->mi[0]->bsize = bsize;
   xd->mi[0]->ref_frame[0] = INTRA_FRAME;
@@ -761,8 +763,10 @@
 
     // Reset to last frame as reference buffer.
     xd->plane[0].pre[0].buf = last_frame->y_buffer + recon_yoffset;
-    xd->plane[1].pre[0].buf = last_frame->u_buffer + recon_uvoffset;
-    xd->plane[2].pre[0].buf = last_frame->v_buffer + recon_uvoffset;
+    if (av1_num_planes(&cpi->common) > 1) {
+      xd->plane[1].pre[0].buf = last_frame->u_buffer + recon_uvoffset;
+      xd->plane[2].pre[0].buf = last_frame->v_buffer + recon_uvoffset;
+    }
   } else {
     stats->sr_coded_error += motion_error;
   }
@@ -1196,8 +1200,10 @@
 
     // Adjust to the next column of MBs.
     x->plane[0].src.buf += fp_block_size_width;
-    x->plane[1].src.buf += uv_mb_height;
-    x->plane[2].src.buf += uv_mb_height;
+    if (num_planes > 1) {
+      x->plane[1].src.buf += uv_mb_height;
+      x->plane[2].src.buf += uv_mb_height;
+    }
 
     recon_yoffset += fp_block_size_width;
     src_yoffset += fp_block_size_width;