diff --git a/libavcodec/hnm4video.c b/libavcodec/hnm4video.c
index 0d3fa7d1e8..dd7504c514 100644
--- a/libavcodec/hnm4video.c
+++ b/libavcodec/hnm4video.c
@@ -507,5 +507,5 @@ const AVCodec ff_hnm4_video_decoder = {
     .close          = hnm_decode_end,
     .decode         = hnm_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,
 };