diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 1c44f87837..2d62b5b4f0 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -2085,7 +2085,8 @@ int av_write_frame(AVFormatContext *s, AVPacket *pkt);
  *            correct values.
  *            @endparblock
  *
- * @return 0 on success, a negative AVERROR on error.
+ * @return 0 on success, a negative AVERROR on error. Libavformat will always
+ *         take care of freeing the packet, even if this function fails.
  *
  * @see av_write_frame(), AVFormatContext.max_interleave_delta
  */
diff --git a/libavformat/mux.c b/libavformat/mux.c
index 0b89406f4e..14e72e8cd8 100644
--- a/libavformat/mux.c
+++ b/libavformat/mux.c
@@ -808,22 +808,26 @@ int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt)
 
     ret = check_packet(s, pkt);
     if (ret < 0)
-        return ret;
+        goto fail;
 
     if (pkt) {
         AVStream *st = s->streams[pkt->stream_index];
 
         //FIXME/XXX/HACK drop zero sized packets
-        if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO && pkt->size == 0)
-            return 0;
+        if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO && pkt->size == 0) {
+            ret = 0;
+            goto fail;
+        }
 
         av_dlog(s, "av_interleaved_write_frame size:%d dts:%s pts:%s\n",
                 pkt->size, av_ts2str(pkt->dts), av_ts2str(pkt->pts));
         if ((ret = compute_pkt_fields2(s, st, pkt)) < 0 && !(s->oformat->flags & AVFMT_NOTIMESTAMPS))
-            return ret;
+            goto fail;
 
-        if (pkt->dts == AV_NOPTS_VALUE && !(s->oformat->flags & AVFMT_NOTIMESTAMPS))
-            return AVERROR(EINVAL);
+        if (pkt->dts == AV_NOPTS_VALUE && !(s->oformat->flags & AVFMT_NOTIMESTAMPS)) {
+            ret = AVERROR(EINVAL);
+            goto fail;
+        }
     } else {
         av_dlog(s, "av_interleaved_write_frame FLUSH\n");
         flush = 1;
@@ -832,6 +836,11 @@ int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt)
     for (;; ) {
         AVPacket opkt;
         int ret = interleave_packet(s, &opkt, pkt, flush);
+        if (pkt) {
+            memset(pkt, 0, sizeof(*pkt));
+            av_init_packet(pkt);
+            pkt = NULL;
+        }
         if (ret <= 0) //FIXME cleanup needed for ret<0 ?
             return ret;
 
@@ -840,13 +849,15 @@ int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt)
             s->streams[opkt.stream_index]->nb_frames++;
 
         av_free_packet(&opkt);
-        pkt = NULL;
 
         if (ret < 0)
             return ret;
         if(s->pb && s->pb->error)
             return s->pb->error;
     }
+fail:
+    av_packet_unref(pkt);
+    return ret;
 }
 
 int av_write_trailer(AVFormatContext *s)