diff --git a/libavcodec/a64multienc.c b/libavcodec/a64multienc.c
index 2643b1a2db66a0619d63c309458c2c7acfcfee89..f9c4f36e7d0c48eb33b7b26ebfa4c6b04c18d995 100644
--- a/libavcodec/a64multienc.c
+++ b/libavcodec/a64multienc.c
@@ -28,6 +28,7 @@
 #include "a64tables.h"
 #include "elbg.h"
 #include "internal.h"
+#include "libavutil/avassert.h"
 #include "libavutil/common.h"
 #include "libavutil/intreadwrite.h"
 
@@ -385,6 +386,7 @@ static int a64multi_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
         pkt->pts = pkt->dts = c->next_pts;
         c->next_pts         = AV_NOPTS_VALUE;
 
+        av_assert0(pkt->size >= req_size);
         pkt->size   = req_size;
         pkt->flags |= AV_PKT_FLAG_KEY;
         *got_packet = !!req_size;