diff --git a/libavcodec/snow.h b/libavcodec/snow.h
index 6f1fca378c..12aad1874a 100644
--- a/libavcodec/snow.h
+++ b/libavcodec/snow.h
@@ -298,6 +298,8 @@ static av_always_inline void add_yblock(SnowContext *s, int sliced, slice_buffer
     BlockNode *lb= lt+b_stride;
     BlockNode *rb= lb+1;
     uint8_t *block[4];
+    // When src_stride is large enough, it is possible to interleave the blocks.
+    // Otherwise the blocks are written sequentially in the tmp buffer.
     int tmp_step= src_stride >= 7*MB_SIZE ? MB_SIZE : MB_SIZE*src_stride;
     uint8_t *tmp = s->scratchbuf;
     uint8_t *ptmp;
@@ -341,8 +343,6 @@ static av_always_inline void add_yblock(SnowContext *s, int sliced, slice_buffer
 
     if(b_w<=0 || b_h<=0) return;
 
-    av_assert2(src_stride > 2*MB_SIZE + 5);
-
     if(!sliced && offset_dst)
         dst += src_x + src_y*dst_stride;
     dst8+= src_x + src_y*src_stride;