diff --git a/libavformat/matroska.h b/libavformat/matroska.h
index 613e27a4e7..1b84e90a0d 100644
--- a/libavformat/matroska.h
+++ b/libavformat/matroska.h
@@ -203,9 +203,6 @@ typedef struct CodecMime{
     enum CodecID id;
 }CodecMime;
 
-#define MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC   "V_MS/VFW/FOURCC"
-#define MATROSKA_CODEC_ID_AUDIO_ACM          "A_MS/ACM"
-
 /* max. depth in the EBML tree structure */
 #define EBML_MAX_DEPTH 16
 
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 8e8dfc7d58..d90162b404 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1138,12 +1138,12 @@ static int matroska_read_header(AVFormatContext *s, AVFormatParameters *ap)
         if (st == NULL)
             return AVERROR(ENOMEM);
 
-        if (!strcmp(track->codec_id, MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC)
+        if (!strcmp(track->codec_id, "V_MS/VFW/FOURCC")
             && track->codec_priv.size >= 40
             && track->codec_priv.data != NULL) {
             track->video.fourcc = AV_RL32(track->codec_priv.data + 16);
             codec_id = codec_get_id(codec_bmp_tags, track->video.fourcc);
-        } else if (!strcmp(track->codec_id, MATROSKA_CODEC_ID_AUDIO_ACM)
+        } else if (!strcmp(track->codec_id, "A_MS/ACM")
                    && track->codec_priv.size >= 18
                    && track->codec_priv.data != NULL) {
             uint16_t tag = AV_RL16(track->codec_priv.data);
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 24bcfdb527..8e1c8e5a0e 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -587,7 +587,7 @@ static int mkv_write_tracks(AVFormatContext *s)
                     put_ebml_string(pb, MATROSKA_ID_CODECID, "V_QUICKTIME");
                 else if (!native_id)
                     // if there is no mkv-specific codec ID, use VFW mode
-                    put_ebml_string(pb, MATROSKA_ID_CODECID, MATROSKA_CODEC_ID_VIDEO_VFW_FOURCC);
+                    put_ebml_string(pb, MATROSKA_ID_CODECID, "V_MS/VFW/FOURCC");
 
                 subinfo = start_ebml_master(pb, MATROSKA_ID_TRACKVIDEO, 0);
                 // XXX: interlace flag?
@@ -607,7 +607,7 @@ static int mkv_write_tracks(AVFormatContext *s)
 
                 if (!native_id)
                     // no mkv-specific ID, use ACM mode
-                    put_ebml_string(pb, MATROSKA_ID_CODECID, MATROSKA_CODEC_ID_AUDIO_ACM);
+                    put_ebml_string(pb, MATROSKA_ID_CODECID, "A_MS/ACM");
 
                 subinfo = start_ebml_master(pb, MATROSKA_ID_TRACKAUDIO, 0);
                 put_ebml_uint  (pb, MATROSKA_ID_AUDIOCHANNELS    , codec->channels);