diff --git a/libavcodec/mss3.c b/libavcodec/mss3.c
index 0ce7c96121..8ac2c23d35 100644
--- a/libavcodec/mss3.c
+++ b/libavcodec/mss3.c
@@ -869,5 +869,5 @@ const AVCodec ff_msa1_decoder = {
     .close          = mss3_decode_end,
     .decode         = mss3_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
-    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
 };