diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index f21dd90305..a9ea1d8e1f 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1687,6 +1687,7 @@ int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp,
  * or if stream_index is -1, in AV_TIME_BASE units.
  * If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
  * keyframes (this may not be supported by all demuxers).
+ * If flags contain AVSEEK_FLAG_BACKWARD, it is ignored.
  *
  * @param stream_index index of the stream which is used as time base reference
  * @param min_ts smallest acceptable timestamp
diff --git a/libavformat/concatdec.c b/libavformat/concatdec.c
index 5359ad149d..78362e2c65 100644
--- a/libavformat/concatdec.c
+++ b/libavformat/concatdec.c
@@ -341,7 +341,7 @@ static int real_seek(AVFormatContext *avf, int stream,
         return ret;
 
     ret = try_seek(avf, stream, min_ts, ts, max_ts, flags);
-    if (ret < 0 && !(flags & AVSEEK_FLAG_BACKWARD) &&
+    if (ret < 0 &&
         left < cat->nb_files - 1 &&
         cat->files[left + 1].start_time < max_ts) {
         if ((ret = open_file(avf, left + 1)) < 0)
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index da34ea7677..371b9d0bf2 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -705,7 +705,7 @@ static int mkv_write_tracks(AVFormatContext *s)
                 break;
             default:
                 av_log(s, AV_LOG_ERROR, "Only audio, video, and subtitles are supported for Matroska.\n");
-                break;
+                return AVERROR(EINVAL);
         }
         ret = mkv_write_codecprivate(s, pb, codec, native_id, qt_id);
         if (ret < 0) return ret;
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 71246a9db2..89a5105063 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -2135,7 +2135,19 @@ static int seek_frame_internal(AVFormatContext *s, int stream_index,
 
 int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
 {
-    int ret = seek_frame_internal(s, stream_index, timestamp, flags);
+    int ret;
+
+    if (s->iformat->read_seek2 && !s->iformat->read_seek) {
+        int64_t min_ts = INT64_MIN, max_ts = INT64_MAX;
+        if ((flags & AVSEEK_FLAG_BACKWARD))
+            max_ts = timestamp;
+        else
+            min_ts = timestamp;
+        return avformat_seek_file(s, stream_index, min_ts, timestamp, max_ts,
+                                  flags & ~AVSEEK_FLAG_BACKWARD);
+    }
+
+    ret = seek_frame_internal(s, stream_index, timestamp, flags);
 
     if (ret >= 0)
         ret = avformat_queue_attached_pictures(s);
@@ -2152,6 +2164,7 @@ int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int
 
     if(s->seek2any>0)
         flags |= AVSEEK_FLAG_ANY;
+    flags &= ~AVSEEK_FLAG_BACKWARD;
 
     if (s->iformat->read_seek2) {
         int ret;