diff --git a/libavcodec/mpegvideo_xvmc.c b/libavcodec/mpegvideo_xvmc.c
index ade72739cd..df95dff8f9 100644
--- a/libavcodec/mpegvideo_xvmc.c
+++ b/libavcodec/mpegvideo_xvmc.c
@@ -316,14 +316,11 @@ void ff_xvmc_decode_mb(MpegEncContext *s)
     }
     render->filled_mv_blocks_num++;
 
-
-    if (render->filled_mv_blocks_num > render->allocated_mv_blocks)
-        av_log(s->avctx, AV_LOG_ERROR,
-               "Not enough space to store mv blocks allocated.\n");
-
-    if (render->next_free_data_block_num > render->allocated_data_blocks)
-        av_log(s->avctx, AV_LOG_ERROR,
-               "Offset to next data block exceeds number of allocated data blocks.\n");
+    assert(render->filled_mv_blocks_num     <= render->allocated_mv_blocks);
+    assert(render->next_free_data_block_num <= render->allocated_data_blocks);
+    /* The above conditions should not be able to fail as long as this function
+     * is used and the following 'if ()' automatically calls a callback to free
+     * blocks. */
 
 
     if (render->filled_mv_blocks_num == render->allocated_mv_blocks)