diff --git a/libavformat/matroska.c b/libavformat/matroska.c
index 5e9a6cade3..ea91ed7494 100644
--- a/libavformat/matroska.c
+++ b/libavformat/matroska.c
@@ -24,6 +24,7 @@
 const CodecTags ff_mkv_codec_tags[]={
     {"A_AAC"            , CODEC_ID_AAC},
     {"A_AC3"            , CODEC_ID_AC3},
+    {"A_ALAC"           , CODEC_ID_ALAC},
     {"A_DTS"            , CODEC_ID_DTS},
     {"A_EAC3"           , CODEC_ID_EAC3},
     {"A_FLAC"           , CODEC_ID_FLAC},
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 2c954afa05..0f1808773b 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1580,6 +1580,18 @@ static int matroska_read_header(AVFormatContext *s)
                    && (track->codec_priv.data != NULL)) {
             fourcc = AV_RL32(track->codec_priv.data);
             codec_id = ff_codec_get_id(ff_codec_movvideo_tags, fourcc);
+        } else if (codec_id == CODEC_ID_ALAC && track->codec_priv.size) {
+            /* Only ALAC's magic cookie is stored in Matroska's track headers.
+               Create the "atom size", "tag", and "tag version" fields the
+               decoder expects manually. */
+            extradata_size = 12 + track->codec_priv.size;
+            extradata = av_mallocz(extradata_size);
+            if (extradata == NULL)
+                return AVERROR(ENOMEM);
+            AV_WB32(extradata, extradata_size);
+            memcpy(&extradata[4], "alac", 4);
+            AV_WB32(&extradata[8], 0);
+            memcpy(&extradata[12], track->codec_priv.data, track->codec_priv.size);
         } else if (codec_id == CODEC_ID_PCM_S16BE) {
             switch (track->audio.bitdepth) {
             case  8:  codec_id = CODEC_ID_PCM_U8;     break;