diff --git a/proposals/4108-oidc-qr-login.md b/proposals/4108-oidc-qr-login.md
index f8ded79a1..4a8ccc089 100644
--- a/proposals/4108-oidc-qr-login.md
+++ b/proposals/4108-oidc-qr-login.md
@@ -1420,7 +1420,7 @@ Does the new device/client need to accept the T&Cs of the "guest" homeserver?
 
 #### Other existing protocols
 
-One could try and do something with STUN or TURN or [COAP](http://coap.technology/).
+One could try and do something with STUN or TURN or [COAP](https://datatracker.ietf.org/doc/html/rfc7252).
 
 #### Implementation details