diff --git a/libavcodec/m101.c b/libavcodec/m101.c
index 795a4fba63..dd0ace76f5 100644
--- a/libavcodec/m101.c
+++ b/libavcodec/m101.c
@@ -113,4 +113,5 @@ const AVCodec ff_m101_decoder = {
     .init           = m101_decode_init,
     .decode         = m101_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };