diff --git a/common.c b/common.c
index 7e0b0f1..e885945 100644
--- a/common.c
+++ b/common.c
@@ -804,7 +804,8 @@ socks_5_auth_start (struct socks_connector *self)
 	str_append_c (wb, 0x05);          // version
 	str_append_c (wb, 1 + can_auth);  // number of authentication methods
 	str_append_c (wb, 0x00);          // no authentication required
-	str_append_c (wb, 0x02);          // username/password
+	if (can_auth)
+		str_append_c (wb, 0x02);      // username/password
 
 	self->on_data = socks_5_auth_finish;
 	return true;