diff --git a/libavcodec/dvdsubdec.c b/libavcodec/dvdsubdec.c
index e164745561..52259f0730 100644
--- a/libavcodec/dvdsubdec.c
+++ b/libavcodec/dvdsubdec.c
@@ -764,4 +764,5 @@ const AVCodec ff_dvdsub_decoder = {
     .decode         = dvdsub_decode,
     .flush          = dvdsub_flush,
     .priv_class     = &dvdsub_class,
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };