diff --git a/changelog.d/5210.feature b/changelog.d/5210.feature
index a7476bf9b94a2a7d8ffc23c4fb06d7ce34ccb9f1..c78325a6acbb57416a7a32651db40e5e09ec5368 100644
--- a/changelog.d/5210.feature
+++ b/changelog.d/5210.feature
@@ -1 +1 @@
-Add a new room version which uses a new event ID format.
+Add a room version 4 which uses a new event ID format, as per [MSC2002](https://github.com/matrix-org/matrix-doc/pull/2002).
diff --git a/changelog.d/5217.feature b/changelog.d/5217.feature
new file mode 100644
index 0000000000000000000000000000000000000000..c78325a6acbb57416a7a32651db40e5e09ec5368
--- /dev/null
+++ b/changelog.d/5217.feature
@@ -0,0 +1 @@
+Add a room version 4 which uses a new event ID format, as per [MSC2002](https://github.com/matrix-org/matrix-doc/pull/2002).
diff --git a/synapse/api/room_versions.py b/synapse/api/room_versions.py
index 485b3d0237b985b0244917d3430b2956b26d1990..b2895355a81ade9a3cea9cc3fd0e19aa74754a60 100644
--- a/synapse/api/room_versions.py
+++ b/synapse/api/room_versions.py
@@ -77,9 +77,9 @@ class RoomVersions(object):
         EventFormatVersions.V2,
         StateResolutionVersions.V2,
     )
-    EVENTID_NOSLASH_TEST = RoomVersion(
-        "eventid-noslash-test",
-        RoomDisposition.UNSTABLE,
+    V4 = RoomVersion(
+        "4",
+        RoomDisposition.STABLE,
         EventFormatVersions.V3,
         StateResolutionVersions.V2,
     )
@@ -95,6 +95,6 @@ KNOWN_ROOM_VERSIONS = {
         RoomVersions.V2,
         RoomVersions.V3,
         RoomVersions.STATE_V2_TEST,
-        RoomVersions.EVENTID_NOSLASH_TEST,
+        RoomVersions.V4,
     )
 }   # type: dict[str, RoomVersion]