diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
index 0f234bb0b5..bdb332c71a 100644
--- a/libavformat/dashenc.c
+++ b/libavformat/dashenc.c
@@ -1089,7 +1089,6 @@ AVOutputFormat ff_dash_muxer = {
     .write_packet   = dash_write_packet,
     .write_trailer  = dash_write_trailer,
     .deinit         = dash_free,
-    .codec_tag      = (const AVCodecTag* const []){ ff_mp4_obj_type, 0 },
     .check_bitstream = dash_check_bitstream,
     .priv_class     = &dash_class,
 };
diff --git a/libavformat/smoothstreamingenc.c b/libavformat/smoothstreamingenc.c
index dabd1ea304..083af49212 100644
--- a/libavformat/smoothstreamingenc.c
+++ b/libavformat/smoothstreamingenc.c
@@ -647,6 +647,5 @@ AVOutputFormat ff_smoothstreaming_muxer = {
     .write_header   = ism_write_header,
     .write_packet   = ism_write_packet,
     .write_trailer  = ism_write_trailer,
-    .codec_tag      = (const AVCodecTag* const []){ ff_mp4_obj_type, 0 },
     .priv_class     = &ism_class,
 };