diff --git a/federationapi/routing/join.go b/federationapi/routing/join.go
index 369e19aed..2fcb929ad 100644
--- a/federationapi/routing/join.go
+++ b/federationapi/routing/join.go
@@ -88,9 +88,22 @@ func MakeJoin(
 		}
 	}
 
+	// Get the room version of the room being joined
+	vQueryReq := api.QueryRoomVersionForRoomIDRequest{RoomID: roomID}
+	vQueryRes := api.QueryRoomVersionForRoomIDResponse{}
+	if e := query.QueryRoomVersionForRoomID(httpReq.Context(), &vQueryReq, &vQueryRes); e != nil {
+		return util.JSONResponse{
+			Code: http.StatusInternalServerError,
+			JSON: jsonerror.Unknown(err.Error()),
+		}
+	}
+
 	return util.JSONResponse{
 		Code: http.StatusOK,
-		JSON: map[string]interface{}{"event": builder},
+		JSON: map[string]interface{}{
+			"event":        builder,
+			"room_version": vQueryRes.RoomVersion,
+		},
 	}
 }
 
diff --git a/roomserver/input/events.go b/roomserver/input/events.go
index 7f4cfb4a7..80cf6f1a2 100644
--- a/roomserver/input/events.go
+++ b/roomserver/input/events.go
@@ -75,7 +75,7 @@ type RoomEventDatabase interface {
 	// Look up the room version from the database.
 	GetRoomVersionForRoom(
 		ctx context.Context, roomNID types.RoomNID,
-	) (state.StateResolutionVersion, error)
+	) (int64, error)
 }
 
 // OutputRoomEventWriter has the APIs needed to write an event to the output logs.
diff --git a/roomserver/query/query.go b/roomserver/query/query.go
index a891af5fa..6e15a9168 100644
--- a/roomserver/query/query.go
+++ b/roomserver/query/query.go
@@ -92,7 +92,7 @@ type RoomserverQueryAPIDatabase interface {
 	// Look up the room version from the database.
 	GetRoomVersionForRoom(
 		ctx context.Context, roomNID types.RoomNID,
-	) (state.StateResolutionVersion, error)
+	) (int64, error)
 	// Get the room NID for a given event ID.
 	RoomNIDForEventID(
 		ctx context.Context, eventID string,
@@ -627,17 +627,21 @@ func (r *RoomserverQueryAPI) QueryStateAndAuthChain(
 	request *api.QueryStateAndAuthChainRequest,
 	response *api.QueryStateAndAuthChainResponse,
 ) error {
-	// TODO: get the correct room version
-	roomState, err := state.GetStateResolutionAlgorithm(state.StateResolutionAlgorithmV1, r.DB)
+	roomNID, err := r.DB.RoomNID(ctx, request.RoomID)
+	if err != nil {
+		return err
+	}
+	roomVersion, err := r.DB.GetRoomVersionForRoom(ctx, roomNID)
+	if err != nil {
+		return err
+	}
+	roomState, err := state.GetStateResolutionAlgorithm(roomVersion, r.DB)
 	if err != nil {
 		return err
 	}
 
 	response.QueryStateAndAuthChainRequest = *request
-	roomNID, err := r.DB.RoomNID(ctx, request.RoomID)
-	if err != nil {
-		return err
-	}
+
 	if roomNID == 0 {
 		return nil
 	}
diff --git a/roomserver/state/state.go b/roomserver/state/state.go
index 4449cc83c..d5dfb8bfc 100644
--- a/roomserver/state/state.go
+++ b/roomserver/state/state.go
@@ -38,13 +38,13 @@ const (
 )
 
 func GetStateResolutionAlgorithm(
-	version StateResolutionVersion, db database.RoomStateDatabase,
+	version int64, db database.RoomStateDatabase,
 ) (StateResolutionImpl, error) {
 	switch version {
-	case StateResolutionAlgorithmV1:
-		fallthrough
-	case StateResolutionAlgorithmV2:
-		return Prepare(db, version), nil
+	case 1:
+		return Prepare(db, StateResolutionAlgorithmV1), nil
+	case 2, 3, 4, 5:
+		return Prepare(db, StateResolutionAlgorithmV2), nil
 	default:
 		return nil, errors.New("unsupported room version")
 	}
diff --git a/roomserver/storage/interface.go b/roomserver/storage/interface.go
index f03d6feab..ad290017c 100644
--- a/roomserver/storage/interface.go
+++ b/roomserver/storage/interface.go
@@ -46,4 +46,6 @@ type Database interface {
 	GetMembershipEventNIDsForRoom(ctx context.Context, roomNID types.RoomNID, joinOnly bool) ([]types.EventNID, error)
 	EventsFromIDs(ctx context.Context, eventIDs []string) ([]types.Event, error)
 	GetRoomVersionForRoom(ctx context.Context, roomNID types.RoomNID) (int64, error)
+	RoomNIDForEventID(ctx context.Context, eventID string) (types.RoomNID, error)
+	RoomNIDForEventNID(ctx context.Context, eventNID types.EventNID) (types.RoomNID, error)
 }
diff --git a/roomserver/storage/postgres/rooms_table.go b/roomserver/storage/postgres/rooms_table.go
index 7616af43e..8f52d3507 100644
--- a/roomserver/storage/postgres/rooms_table.go
+++ b/roomserver/storage/postgres/rooms_table.go
@@ -21,7 +21,6 @@ import (
 
 	"github.com/lib/pq"
 	"github.com/matrix-org/dendrite/common"
-	"github.com/matrix-org/dendrite/roomserver/state"
 	"github.com/matrix-org/dendrite/roomserver/types"
 )
 
@@ -166,8 +165,8 @@ func (s *roomStatements) updateLatestEventNIDs(
 
 func (s *roomStatements) selectRoomVersionForRoomNID(
 	ctx context.Context, txn *sql.Tx, roomNID types.RoomNID,
-) (state.StateResolutionVersion, error) {
-	var roomVersion state.StateResolutionVersion
+) (int64, error) {
+	var roomVersion int64
 	stmt := common.TxStmt(txn, s.selectRoomVersionForRoomNIDStmt)
 	err := stmt.QueryRowContext(ctx, roomNID).Scan(&roomVersion)
 	return roomVersion, err
diff --git a/roomserver/storage/postgres/storage.go b/roomserver/storage/postgres/storage.go
index 2e589d0d4..4499388a0 100644
--- a/roomserver/storage/postgres/storage.go
+++ b/roomserver/storage/postgres/storage.go
@@ -25,7 +25,6 @@ import (
 	_ "github.com/lib/pq"
 	"github.com/matrix-org/dendrite/common"
 	"github.com/matrix-org/dendrite/roomserver/api"
-	"github.com/matrix-org/dendrite/roomserver/state"
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/dendrite/roomserver/version"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -737,7 +736,7 @@ func (d *Database) EventsFromIDs(ctx context.Context, eventIDs []string) ([]type
 
 func (d *Database) GetRoomVersionForRoom(
 	ctx context.Context, roomNID types.RoomNID,
-) (state.StateResolutionVersion, error) {
+) (int64, error) {
 	return d.statements.selectRoomVersionForRoomNID(
 		ctx, nil, roomNID,
 	)
diff --git a/roomserver/storage/sqlite3/rooms_table.go b/roomserver/storage/sqlite3/rooms_table.go
index 4a9ef6654..50ddb40e8 100644
--- a/roomserver/storage/sqlite3/rooms_table.go
+++ b/roomserver/storage/sqlite3/rooms_table.go
@@ -21,7 +21,6 @@ import (
 	"encoding/json"
 
 	"github.com/matrix-org/dendrite/common"
-	"github.com/matrix-org/dendrite/roomserver/state"
 	"github.com/matrix-org/dendrite/roomserver/types"
 )
 
@@ -158,8 +157,8 @@ func (s *roomStatements) updateLatestEventNIDs(
 
 func (s *roomStatements) selectRoomVersionForRoomNID(
 	ctx context.Context, txn *sql.Tx, roomNID types.RoomNID,
-) (state.StateResolutionVersion, error) {
-	var roomVersion state.StateResolutionVersion
+) (int64, error) {
+	var roomVersion int64
 	stmt := common.TxStmt(txn, s.selectRoomVersionForRoomNIDStmt)
 	err := stmt.QueryRowContext(ctx, roomNID).Scan(&roomVersion)
 	return roomVersion, err
diff --git a/roomserver/storage/sqlite3/storage.go b/roomserver/storage/sqlite3/storage.go
index 3ed193b7e..b3f375887 100644
--- a/roomserver/storage/sqlite3/storage.go
+++ b/roomserver/storage/sqlite3/storage.go
@@ -25,7 +25,6 @@ import (
 
 	"github.com/matrix-org/dendrite/common"
 	"github.com/matrix-org/dendrite/roomserver/api"
-	"github.com/matrix-org/dendrite/roomserver/state"
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/dendrite/roomserver/version"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -890,7 +889,7 @@ func (d *Database) EventsFromIDs(ctx context.Context, eventIDs []string) ([]type
 
 func (d *Database) GetRoomVersionForRoom(
 	ctx context.Context, roomNID types.RoomNID,
-) (state.StateResolutionVersion, error) {
+) (int64, error) {
 	return d.statements.selectRoomVersionForRoomNID(
 		ctx, nil, roomNID,
 	)