diff --git a/libavformat/http.c b/libavformat/http.c
index f88d58f024..3d477366ae 100644
--- a/libavformat/http.c
+++ b/libavformat/http.c
@@ -609,7 +609,7 @@ static int http_connect(URLContext *h, const char *path, const char *local_path,
          * send Expect: 100-continue to get the 401 response including the
          * WWW-Authenticate header, or an 100 continue if no auth actually
          * is needed. */
-        if (auth && s->auth_state.auth_type == HTTP_AUTH_NONE &&
+        if (*auth && s->auth_state.auth_type == HTTP_AUTH_NONE &&
             s->http_code != 401)
             send_expect_100 = 1;
     }