diff --git a/clientapi/routing/createroom.go b/clientapi/routing/createroom.go
index a384e0757..18ca2347d 100644
--- a/clientapi/routing/createroom.go
+++ b/clientapi/routing/createroom.go
@@ -200,7 +200,7 @@ func createRoom(
 		if createRequest.Preset == spec.PresetTrustedPrivateChat {
 			additionalCreators = createRequest.Invite
 		}
-		createContent, err := roomserverAPI.GenerateCreateContent(ctx, createRequest.RoomVersion, userID.String(), createRequest.CreationContent, additionalCreators)
+		createContent, err := roomserverAPI.GenerateCreateContent(ctx, roomVersion, userID.String(), createRequest.CreationContent, additionalCreators)
 		if err != nil {
 			util.GetLogger(ctx).WithError(err).Error("GenerateCreateContent failed")
 			return util.JSONResponse{
diff --git a/federationapi/routing/backfill.go b/federationapi/routing/backfill.go
index 945975d6f..20f5923df 100644
--- a/federationapi/routing/backfill.go
+++ b/federationapi/routing/backfill.go
@@ -37,7 +37,7 @@ func Backfill(
 	var err error
 
 	// Check the room ID's format.
-	if _, _, err = gomatrixserverlib.SplitID('!', roomID); err != nil {
+	if _, err = spec.NewRoomID(roomID); err != nil {
 		return util.JSONResponse{
 			Code: http.StatusBadRequest,
 			JSON: spec.MissingParam("Bad room ID: " + err.Error()),
diff --git a/federationapi/routing/threepid.go b/federationapi/routing/threepid.go
index c2b4fa045..efde7014a 100644
--- a/federationapi/routing/threepid.go
+++ b/federationapi/routing/threepid.go
@@ -394,10 +394,11 @@ func sendToRemoteServer(
 	}
 	// Fallback to the room's server if the sender's domain is the same as
 	// the current server's
-	_, remoteServers[1], err = gomatrixserverlib.SplitID('!', inv.RoomID)
+	roomID, err := spec.NewRoomID(inv.RoomID)
 	if err != nil {
 		return
 	}
+	remoteServers[1] = roomID.Domain()
 
 	for _, server := range remoteServers {
 		err = federation.ExchangeThirdPartyInvite(ctx, cfg.Matrix.ServerName, server, proto)
diff --git a/roomserver/internal/perform/perform_admin.go b/roomserver/internal/perform/perform_admin.go
index da8c92a6b..9e7cc865e 100644
--- a/roomserver/internal/perform/perform_admin.go
+++ b/roomserver/internal/perform/perform_admin.go
@@ -192,7 +192,7 @@ func (r *Admin) PerformAdminPurgeRoom(
 	roomID string,
 ) error {
 	// Validate we actually got a room ID and nothing else
-	if _, _, err := gomatrixserverlib.SplitID('!', roomID); err != nil {
+	if _, err := spec.NewRoomID(roomID); err != nil {
 		return err
 	}
 
diff --git a/roomserver/internal/perform/perform_peek.go b/roomserver/internal/perform/perform_peek.go
index d15a90ac3..09da37385 100644
--- a/roomserver/internal/perform/perform_peek.go
+++ b/roomserver/internal/perform/perform_peek.go
@@ -114,11 +114,11 @@ func (r *Peeker) performPeekRoomByID(
 	roomID = req.RoomIDOrAlias
 
 	// Get the domain part of the room ID.
-	_, domain, err := gomatrixserverlib.SplitID('!', roomID)
+	specRoomID, err := spec.NewRoomID(roomID)
 	if err != nil {
 		return "", api.ErrInvalidID{Err: fmt.Errorf("room ID %q is invalid: %w", roomID, err)}
 	}
-
+	domain := specRoomID.Domain()
 	// handle federated peeks
 	// FIXME: don't create an outbound peek if we already have one going.
 	if !r.Cfg.Matrix.IsLocalServerName(domain) {
diff --git a/roomserver/internal/perform/perform_unpeek.go b/roomserver/internal/perform/perform_unpeek.go
index db17937ad..b1e55d049 100644
--- a/roomserver/internal/perform/perform_unpeek.go
+++ b/roomserver/internal/perform/perform_unpeek.go
@@ -49,7 +49,7 @@ func (r *Unpeeker) performUnpeekRoomByID(
 	roomID, userID, deviceID string,
 ) (err error) {
 	// Get the domain part of the room ID.
-	_, _, err = gomatrixserverlib.SplitID('!', roomID)
+	_, err = spec.NewRoomID(roomID)
 	if err != nil {
 		return api.ErrInvalidID{Err: fmt.Errorf("room ID %q is invalid: %w", roomID, err)}
 	}