diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index c63ecdd..4dfcc55 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -107,6 +107,8 @@ typedef struct MatroskaMuxContext {
     const AVClass  *class;
     int             mode;
     AVIOContext   *dyn_bc;
+    AVIOContext     *tags_bc;
+    ebml_master     tags;
     ebml_master     segment;
     int64_t         segment_offset;
     ebml_master     cluster;
@@ -1343,6 +1345,7 @@ static int mkv_write_tag_targets(AVFormatContext *s,
                                  unsigned int elementid, unsigned int uid,
                                  ebml_master *tags, ebml_master* tag)
 {
+    AVIOContext *pb;
     MatroskaMuxContext *mkv = s->priv_data;
     ebml_master targets;
     int ret;
@@ -1351,14 +1354,15 @@ static int mkv_write_tag_targets(AVFormatContext *s,
         ret = mkv_add_seekhead_entry(mkv->main_seekhead, MATROSKA_ID_TAGS, avio_tell(s->pb));
         if (ret < 0) return ret;
 
-        *tags = start_ebml_master(s->pb, MATROSKA_ID_TAGS, 0);
+        start_ebml_master_crc32(s->pb, &mkv->tags_bc, tags, MATROSKA_ID_TAGS, 0);
     }
+    pb = mkv->tags_bc;
 
-    *tag     = start_ebml_master(s->pb, MATROSKA_ID_TAG,        0);
-    targets = start_ebml_master(s->pb, MATROSKA_ID_TAGTARGETS, 0);
+    *tag     = start_ebml_master(pb, MATROSKA_ID_TAG,       0);
+    targets = start_ebml_master(pb, MATROSKA_ID_TAGTARGETS, 0);
     if (elementid)
-        put_ebml_uint(s->pb, elementid, uid);
-    end_ebml_master(s->pb, targets);
+        put_ebml_uint(pb, elementid, uid);
+    end_ebml_master(pb, targets);
     return 0;
 }
 
@@ -1376,6 +1380,7 @@ static int mkv_check_tag_name(const char *name, unsigned int elementid)
 static int mkv_write_tag(AVFormatContext *s, AVDictionary *m, unsigned int elementid,
                          unsigned int uid, ebml_master *tags)
 {
+    MatroskaMuxContext *mkv = s->priv_data;
     ebml_master tag;
     int ret;
     AVDictionaryEntry *t = NULL;
@@ -1386,13 +1391,13 @@ static int mkv_write_tag(AVFormatContext *s, AVDictionary *m, unsigned int eleme
 
     while ((t = av_dict_get(m, "", t, AV_DICT_IGNORE_SUFFIX))) {
         if (mkv_check_tag_name(t->key, elementid)) {
-            ret = mkv_write_simpletag(s->pb, t);
+            ret = mkv_write_simpletag(mkv->tags_bc, t);
             if (ret < 0)
                 return ret;
         }
     }
 
-    end_ebml_master(s->pb, tag);
+    end_ebml_master(mkv->tags_bc, tag);
     return 0;
 }
 
@@ -1410,13 +1415,12 @@ static int mkv_check_tag(AVDictionary *m, unsigned int elementid)
 static int mkv_write_tags(AVFormatContext *s)
 {
     MatroskaMuxContext *mkv = s->priv_data;
-    ebml_master tags = {0};
     int i, ret;
 
     ff_metadata_conv_ctx(s, ff_mkv_metadata_conv, NULL);
 
     if (mkv_check_tag(s->metadata, 0)) {
-        ret = mkv_write_tag(s, s->metadata, 0, 0, &tags);
+        ret = mkv_write_tag(s, s->metadata, 0, 0, &mkv->tags);
         if (ret < 0) return ret;
     }
 
@@ -1426,26 +1430,28 @@ static int mkv_write_tags(AVFormatContext *s)
         if (!mkv_check_tag(st->metadata, MATROSKA_ID_TAGTARGETS_TRACKUID))
             continue;
 
-        ret = mkv_write_tag(s, st->metadata, MATROSKA_ID_TAGTARGETS_TRACKUID, i + 1, &tags);
+        ret = mkv_write_tag(s, st->metadata, MATROSKA_ID_TAGTARGETS_TRACKUID, i + 1, &mkv->tags);
         if (ret < 0) return ret;
     }
 
     if (s->pb->seekable && !mkv->is_live) {
         for (i = 0; i < s->nb_streams; i++) {
+            AVIOContext *pb;
             ebml_master tag_target;
             ebml_master tag;
 
-            mkv_write_tag_targets(s, MATROSKA_ID_TAGTARGETS_TRACKUID, i + 1, &tags, &tag_target);
+            mkv_write_tag_targets(s, MATROSKA_ID_TAGTARGETS_TRACKUID, i + 1, &mkv->tags, &tag_target);
+            pb = mkv->tags_bc;
 
-            tag = start_ebml_master(s->pb, MATROSKA_ID_SIMPLETAG, 0);
-            put_ebml_string(s->pb, MATROSKA_ID_TAGNAME, "DURATION");
-            mkv->stream_duration_offsets[i] = avio_tell(s->pb);
+            tag = start_ebml_master(pb, MATROSKA_ID_SIMPLETAG, 0);
+            put_ebml_string(pb, MATROSKA_ID_TAGNAME, "DURATION");
+            mkv->stream_duration_offsets[i] = avio_tell(pb);
 
             // Reserve space to write duration as a 20-byte string.
             // 2 (ebml id) + 1 (data size) + 20 (data)
-            put_ebml_void(s->pb, 23);
-            end_ebml_master(s->pb, tag);
-            end_ebml_master(s->pb, tag_target);
+            put_ebml_void(pb, 23);
+            end_ebml_master(pb, tag);
+            end_ebml_master(pb, tag_target);
         }
     }
 
@@ -1455,12 +1461,16 @@ static int mkv_write_tags(AVFormatContext *s)
         if (!mkv_check_tag(ch->metadata, MATROSKA_ID_TAGTARGETS_CHAPTERUID))
             continue;
 
-        ret = mkv_write_tag(s, ch->metadata, MATROSKA_ID_TAGTARGETS_CHAPTERUID, ch->id + mkv->chapter_id_offset, &tags);
+        ret = mkv_write_tag(s, ch->metadata, MATROSKA_ID_TAGTARGETS_CHAPTERUID, ch->id + mkv->chapter_id_offset, &mkv->tags);
         if (ret < 0) return ret;
     }
 
-    if (tags.pos)
-        end_ebml_master(s->pb, tags);
+    if (mkv->tags.pos) {
+        if (s->pb->seekable && !mkv->is_live)
+            put_ebml_void(s->pb, avio_tell(mkv->tags_bc) + ((mkv->mode != MODE_WEBM) ? 2 /* ebml id + data size */ + 4 /* CRC32 */ : 0));
+        else
+            end_ebml_master_crc32(s->pb, &mkv->tags_bc, mkv, mkv->tags);
+    }
     return 0;
 }
 
@@ -2236,16 +2246,20 @@ static int mkv_write_trailer(AVFormatContext *s)
                        mkv->stream_durations[i]);
 
                 if (!mkv->is_live && mkv->stream_duration_offsets[i] > 0) {
-                    avio_seek(pb, mkv->stream_duration_offsets[i], SEEK_SET);
+                    avio_seek(mkv->tags_bc, mkv->stream_duration_offsets[i], SEEK_SET);
 
                     snprintf(duration_string, 20, "%02d:%02d:%012.9f",
                              (int) duration_sec / 3600, ((int) duration_sec / 60) % 60,
                              fmod(duration_sec, 60));
 
-                    put_ebml_binary(pb, MATROSKA_ID_TAGSTRING, duration_string, 20);
+                    put_ebml_binary(mkv->tags_bc, MATROSKA_ID_TAGSTRING, duration_string, 20);
                 }
             }
         }
+        if (mkv->tags.pos && !mkv->is_live) {
+            avio_seek(pb, mkv->tags.pos, SEEK_SET);
+            end_ebml_master_crc32(pb, &mkv->tags_bc, mkv, mkv->tags);
+        }
 
         avio_seek(pb, currentpos, SEEK_SET);
     }
diff --git a/tests/ref/fate/rgb24-mkv b/tests/ref/fate/rgb24-mkv
index 01b069c..3cd1887 100644
--- a/tests/ref/fate/rgb24-mkv
+++ b/tests/ref/fate/rgb24-mkv
@@ -1,5 +1,5 @@
-f2ec884f82ecf5754afc0c9a2babe4aa *tests/data/fate/rgb24-mkv.matroska
-58352 tests/data/fate/rgb24-mkv.matroska
+cddd0f9c0efc6592bd3026b8c47471c3 *tests/data/fate/rgb24-mkv.matroska
+58358 tests/data/fate/rgb24-mkv.matroska
 #tb 0: 1/10
 #media_type 0: video
 #codec_id 0: rawvideo
diff --git a/tests/ref/lavf/mka b/tests/ref/lavf/mka
index 1990715..cde5cf9 100644
--- a/tests/ref/lavf/mka
+++ b/tests/ref/lavf/mka
@@ -1,3 +1,3 @@
-927a5d1e7837735271f57b329f1c9d7a *./tests/data/lavf/lavf.mka
-43672 ./tests/data/lavf/lavf.mka
+afd0c76b5fd8ca5ee47d12af7f92d024 *./tests/data/lavf/lavf.mka
+43678 ./tests/data/lavf/lavf.mka
 ./tests/data/lavf/lavf.mka CRC=0x3a1da17e
diff --git a/tests/ref/lavf/mkv b/tests/ref/lavf/mkv
index 951feac..63ed7da 100644
--- a/tests/ref/lavf/mkv
+++ b/tests/ref/lavf/mkv
@@ -1,6 +1,6 @@
-b3599e3229821a84116b4f03f324a08b *./tests/data/lavf/lavf.mkv
-472938 ./tests/data/lavf/lavf.mkv
+aa0fabb3a1564adbdbd27310b1643ca3 *./tests/data/lavf/lavf.mkv
+472944 ./tests/data/lavf/lavf.mkv
 ./tests/data/lavf/lavf.mkv CRC=0xec6c3c68
-c56b90945e6e14a9b4b7f1ab94e3ad28 *./tests/data/lavf/lavf.mkv
-320608 ./tests/data/lavf/lavf.mkv
+85f86c9d5641c2344b9b389f38fad890 *./tests/data/lavf/lavf.mkv
+320614 ./tests/data/lavf/lavf.mkv
 ./tests/data/lavf/lavf.mkv CRC=0xec6c3c68
diff --git a/tests/ref/seek/lavf-mkv b/tests/ref/seek/lavf-mkv
index 7bd1586..26df545 100644
--- a/tests/ref/seek/lavf-mkv
+++ b/tests/ref/seek/lavf-mkv
@@ -1,48 +1,48 @@
-ret: 0         st: 1 flags:1 dts: 0.000000 pts: 0.000000 pos:    818 size:   208
+ret: 0         st: 1 flags:1 dts: 0.000000 pts: 0.000000 pos:    824 size:   208
 ret: 0         st:-1 flags:0  ts:-1.000000
-ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1034 size: 27837
+ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1040 size: 27837
 ret: 0         st:-1 flags:1  ts: 1.894167
-ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292460 size: 27834
+ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292466 size: 27834
 ret: 0         st: 0 flags:0  ts: 0.788000
-ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292460 size: 27834
+ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292466 size: 27834
 ret: 0         st: 0 flags:1  ts:-0.317000
-ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1034 size: 27837
+ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1040 size: 27837
 ret:-1         st: 1 flags:0  ts: 2.577000
 ret: 0         st: 1 flags:1  ts: 1.471000
-ret: 0         st: 1 flags:1 dts: 0.993000 pts: 0.993000 pos: 320301 size:   209
+ret: 0         st: 1 flags:1 dts: 0.993000 pts: 0.993000 pos: 320307 size:   209
 ret: 0         st:-1 flags:0  ts: 0.365002
-ret: 0         st: 0 flags:1 dts: 0.491000 pts: 0.491000 pos: 147007 size: 27925
+ret: 0         st: 0 flags:1 dts: 0.491000 pts: 0.491000 pos: 147013 size: 27925
 ret: 0         st:-1 flags:1  ts:-0.740831
-ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1034 size: 27837
+ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1040 size: 27837
 ret:-1         st: 0 flags:0  ts: 2.153000
 ret: 0         st: 0 flags:1  ts: 1.048000
-ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292460 size: 27834
+ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292466 size: 27834
 ret: 0         st: 1 flags:0  ts:-0.058000
-ret: 0         st: 1 flags:1 dts: 0.000000 pts: 0.000000 pos:    818 size:   208
+ret: 0         st: 1 flags:1 dts: 0.000000 pts: 0.000000 pos:    824 size:   208
 ret: 0         st: 1 flags:1  ts: 2.836000
-ret: 0         st: 1 flags:1 dts: 0.993000 pts: 0.993000 pos: 320301 size:   209
+ret: 0         st: 1 flags:1 dts: 0.993000 pts: 0.993000 pos: 320307 size:   209
 ret:-1         st:-1 flags:0  ts: 1.730004
 ret: 0         st:-1 flags:1  ts: 0.624171
-ret: 0         st: 0 flags:1 dts: 0.491000 pts: 0.491000 pos: 147007 size: 27925
+ret: 0         st: 0 flags:1 dts: 0.491000 pts: 0.491000 pos: 147013 size: 27925
 ret: 0         st: 0 flags:0  ts:-0.482000
-ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1034 size: 27837
+ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1040 size: 27837
 ret: 0         st: 0 flags:1  ts: 2.413000
-ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292460 size: 27834
+ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292466 size: 27834
 ret:-1         st: 1 flags:0  ts: 1.307000
 ret: 0         st: 1 flags:1  ts: 0.201000
-ret: 0         st: 1 flags:1 dts: 0.000000 pts: 0.000000 pos:    818 size:   208
+ret: 0         st: 1 flags:1 dts: 0.000000 pts: 0.000000 pos:    824 size:   208
 ret: 0         st:-1 flags:0  ts:-0.904994
-ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1034 size: 27837
+ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1040 size: 27837
 ret: 0         st:-1 flags:1  ts: 1.989173
-ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292460 size: 27834
+ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292466 size: 27834
 ret: 0         st: 0 flags:0  ts: 0.883000
-ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292460 size: 27834
+ret: 0         st: 0 flags:1 dts: 0.971000 pts: 0.971000 pos: 292466 size: 27834
 ret: 0         st: 0 flags:1  ts:-0.222000
-ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1034 size: 27837
+ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1040 size: 27837
 ret:-1         st: 1 flags:0  ts: 2.672000
 ret: 0         st: 1 flags:1  ts: 1.566000
-ret: 0         st: 1 flags:1 dts: 0.993000 pts: 0.993000 pos: 320301 size:   209
+ret: 0         st: 1 flags:1 dts: 0.993000 pts: 0.993000 pos: 320307 size:   209
 ret: 0         st:-1 flags:0  ts: 0.460008
-ret: 0         st: 0 flags:1 dts: 0.491000 pts: 0.491000 pos: 147007 size: 27925
+ret: 0         st: 0 flags:1 dts: 0.491000 pts: 0.491000 pos: 147013 size: 27925
 ret: 0         st:-1 flags:1  ts:-0.645825
-ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1034 size: 27837
+ret: 0         st: 0 flags:1 dts: 0.011000 pts: 0.011000 pos:   1040 size: 27837
