diff --git a/libavcodec/dvdsubdec.c b/libavcodec/dvdsubdec.c
index 632a53adab..741ea9fd1e 100644
--- a/libavcodec/dvdsubdec.c
+++ b/libavcodec/dvdsubdec.c
@@ -595,6 +595,7 @@ static int dvdsub_decode(AVCodecContext *avctx,
     }
 
     if (is_menu < 0) {
+        ctx->buf_size = 0;
     no_subtitle:
         reset_rects(sub);
         *data_size = 0;