diff --git a/proposals/xxxx-bsspeke-authentication.md b/proposals/3726-bsspeke-authentication.md
similarity index 99%
rename from proposals/xxxx-bsspeke-authentication.md
rename to proposals/3726-bsspeke-authentication.md
index a00fdea27..6e949eb8f 100644
--- a/proposals/xxxx-bsspeke-authentication.md
+++ b/proposals/3726-bsspeke-authentication.md
@@ -1,4 +1,4 @@
-# MSCxxxx: Safer Password-based Authentication with BS-SPEKE
+# MSC3726: Safer Password-based Authentication with BS-SPEKE
 
 In Matrix's `m.login.password` authentication mechanism, the client
 sends their password to the server, using TLS to protect against