diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 70e1d2ca10..384c3a4cb6 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -1197,6 +1197,8 @@ int ffio_open_whitelist(AVIOContext **s, const char *filename, int flags,
     URLContext *h;
     int err;
 
+    *s = NULL;
+
     err = ffurl_open_whitelist(&h, filename, flags, int_cb, options, whitelist, blacklist, NULL);
     if (err < 0)
         return err;