diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
index c5157dc6c7e85fdaabbf4656919021483ec97311..eade740f074193d16df77ada3f0df81b1410b131 100644
--- a/libavformat/hlsenc.c
+++ b/libavformat/hlsenc.c
@@ -219,7 +219,7 @@ static int hls_write_header(AVFormatContext *s)
     if (p)
         *p = '\0';
 
-    av_strlcat(hls->basename, "%d.ts", basename_size);
+    av_strlcat(hls->basename, pattern, basename_size);
 
     if ((ret = hls_mux_init(s)) < 0)
         goto fail;