diff --git a/libavcodec/vmdaudio.c b/libavcodec/vmdaudio.c
index d513479c54..53aef660ef 100644
--- a/libavcodec/vmdaudio.c
+++ b/libavcodec/vmdaudio.c
@@ -237,4 +237,5 @@ const AVCodec ff_vmdaudio_decoder = {
     .init           = vmdaudio_decode_init,
     .decode         = vmdaudio_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };