diff --git a/internal/backends/memory/rooms.go b/internal/backends/memory/rooms.go
index aa6e625..6e1c5be 100644
--- a/internal/backends/memory/rooms.go
+++ b/internal/backends/memory/rooms.go
@@ -20,6 +20,8 @@ type Room struct {
 
 	events []RoomEvent
 
+	server *Backend
+
 	mutex sync.RWMutex
 }
 
@@ -27,7 +29,7 @@ func (room *Room) ID() string {
 	room.mutex.RLock()
 	defer room.mutex.RUnlock()
 
-	return room.id
+	return "!" + room.id + ":" + room.server.hostname
 }
 
 func (room *Room) Name() string {
diff --git a/internal/backends/memory/rooms_test.go b/internal/backends/memory/rooms_test.go
index 5c31cf2..d71529f 100644
--- a/internal/backends/memory/rooms_test.go
+++ b/internal/backends/memory/rooms_test.go
@@ -26,6 +26,7 @@ func TestCreateRoom(t *testing.T) {
 	assert.Equal(t, request.Topic, room.Topic())
 	assert.Equal(t, user.ID(), room.Creator().ID())
 	assert.Equal(t, 1, len(backend.rooms))
+	assert.Equal(t, "!"+room.(*Room).id+":"+backend.hostname, room.ID())
 }
 
 func TestCreateAlreadyExistingRoom(t *testing.T) {