diff --git a/libavformat/jacosubdec.c b/libavformat/jacosubdec.c
index b44e3b7783..828c33057f 100644
--- a/libavformat/jacosubdec.c
+++ b/libavformat/jacosubdec.c
@@ -199,6 +199,7 @@ static int jacosub_read_header(AVFormatContext *s)
 
             sub = ff_subtitles_queue_insert(&jacosub->q, line, len, merge_line);
             if (!sub) {
+                av_bprint_finalize(&header, NULL);
                 ret = AVERROR(ENOMEM);
                 goto fail;
             }