diff --git a/libavcodec/sunrastenc.c b/libavcodec/sunrastenc.c
index c47ea61d03..e4c7c6b090 100644
--- a/libavcodec/sunrastenc.c
+++ b/libavcodec/sunrastenc.c
@@ -222,4 +222,5 @@ const AVCodec ff_sunrast_encoder = {
                                                   AV_PIX_FMT_GRAY8,
                                                   AV_PIX_FMT_MONOWHITE,
                                                   AV_PIX_FMT_NONE },
+    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };