diff --git a/README.md b/README.md
index 872052c..bd5af7d 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # portalgun
 
+https://forum.minetest.net/viewtopic.php?f=11&t=12772
+
 for minetest 0.4.16 or newer<br>
 License: CC0<br>
 Version: 6.3<br>