diff --git a/proposals/XXXX-client-request-device-list.md b/proposals/2638-client-request-device-list.md
similarity index 98%
rename from proposals/XXXX-client-request-device-list.md
rename to proposals/2638-client-request-device-list.md
index b36cfbc620e..fc08e05ee48 100644
--- a/proposals/XXXX-client-request-device-list.md
+++ b/proposals/2638-client-request-device-list.md
@@ -1,4 +1,4 @@
-# MSCXXXX: Ability for clients to request homeservers to resync device lists
+# MSC2638: Ability for clients to request homeservers to resync device lists
 
 With the recent roll out of cross-signing,
 [some](https://github.com/matrix-org/synapse/issues/7418)