     
     internal let cbCharacteristic : CBCharacteristic
     internal let _service         : Service
-    internal let profile          : CharacteristicProfile!
+    internal let profile          : CharacteristicProfile
     
     public var service : Service {
         return self._service

    public func startNotifying() -> Future<Characteristic> {
        self.notificationStateChangedPromise = Promise<Characteristic>()
        if self.propertyEnabled(.Notify) {
            self.service.peripheral.cbPeripheral .setNotifyValue(true, forCharacteristic:self.cbCharacteristic)
        }
        return self.notificationStateChangedPromise.future
    }

    public func stopNotifying() -> Future<Characteristic> {
        self.notificationStateChangedPromise = Promise<Characteristic>()
        if self.propertyEnabled(.Notify) {
            self.service.peripheral.cbPeripheral.setNotifyValue(false, forCharacteristic:self.cbCharacteristic)
        }
        return self.notificationStateChangedPromise.future
    }
