diff --git a/README.md b/README.md
index 13222cc..643d9dc 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Go Bluetooth
 
-[![CircleCI](https://circleci.com/gh/tinygo-org/bluetooth/tree/master.svg?style=svg)](https://circleci.com/gh/tinygo-org/bluetooth/tree/master)
+[![CircleCI](https://circleci.com/gh/tinygo-org/bluetooth/tree/dev.svg?style=svg)](https://circleci.com/gh/tinygo-org/bluetooth/tree/dev)
 [![GoDoc](https://godoc.org/github.com/tinygo-org/bluetooth?status.svg)](https://godoc.org/github.com/tinygo-org/bluetooth)
 
 This package attempts to build a cross-platform Bluetooth Low Energy module for Go. It currently supports the following systems:
@@ -11,7 +11,7 @@ This package attempts to build a cross-platform Bluetooth Low Energy module for
 | Scanning                         | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | Connect to peripheral            | :x:                | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | Write peripheral characteristics | :x:                | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
-| Receive notifications            | :x:                | :heavy_check_mark: | :heavy_check_mark: | :x:                |
+| Receive notifications            | :x:                | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark: |
 | Advertisement                    | :x:                | :heavy_check_mark: | :heavy_check_mark: | :x:                |
 | Local services                   | :x:                | :heavy_check_mark: | :heavy_check_mark: | :x:                |
 | Local characteristics            | :x:                | :heavy_check_mark: | :heavy_check_mark: | :x:                |
@@ -52,7 +52,7 @@ Flashing will then need to be done a bit differently, using the CMSIS-DAP interf
 
 ## API stability
 
-**The API is not stable!** Because many features are not yet implemented and some platforms (e.g. MacOS) are not yet supported, it's hard to say what a good API will be. Therefore, if you want stability you should pick a particular git commit and use that. Go modules can be useful for this purpose.
+**The API is not stable!** Because many features are not yet implemented and some platforms (e.g. Windows and macOS) are not yet fully supported, it's hard to say what a good API will be. Therefore, if you want stability you should pick a particular git commit and use that. Go modules can be useful for this purpose.
 
 Some things that will probably change:
 
diff --git a/gap_darwin.go b/gap_darwin.go
index 039f3ff..46413c9 100644
--- a/gap_darwin.go
+++ b/gap_darwin.go
@@ -85,6 +85,9 @@ type Device struct {
 
 	servicesChan chan error
 	charsChan    chan error
+
+	services        map[UUID]*DeviceService
+	characteristics map[UUID]*DeviceCharacteristic
 }
 
 // Connect starts a connection attempt to the given peripheral device address.
@@ -142,5 +145,10 @@ func (pd *peripheralDelegate) DidDiscoverCharacteristics(prph cbgo.Peripheral, s
 // DidUpdateValueForCharacteristic is called when the characteristic for a Service
 // for a Peripheral receives a notification with a new value.
 func (pd *peripheralDelegate) DidUpdateValueForCharacteristic(prph cbgo.Peripheral, chr cbgo.Characteristic, err error) {
-	// TODO: implement this
+	uuid, _ := ParseUUID(chr.UUID().String())
+	if char, ok := pd.d.characteristics[uuid]; ok {
+		if char != nil && char.callback != nil {
+			go char.callback(chr.Value())
+		}
+	}
 }
diff --git a/gattc_darwin.go b/gattc_darwin.go
index ad4a685..6beba58 100644
--- a/gattc_darwin.go
+++ b/gattc_darwin.go
@@ -20,6 +20,9 @@ func (d *Device) DiscoverServices(uuids []UUID) ([]DeviceService, error) {
 
 	d.prph.DiscoverServices(cbuuids)
 
+	// clear cache of services
+	d.services = make(map[UUID]*DeviceService)
+
 	// wait on channel for service discovery
 	select {
 	case <-d.servicesChan:
@@ -32,6 +35,7 @@ func (d *Device) DiscoverServices(uuids []UUID) ([]DeviceService, error) {
 				service: dsvc,
 			}
 			svcs = append(svcs, svc)
+			d.services[svc.UUID] = &svc
 		}
 		return svcs, nil
 	case <-time.NewTimer(10 * time.Second).C:
@@ -63,6 +67,9 @@ func (s *DeviceService) DiscoverCharacteristics(uuids []UUID) ([]DeviceCharacter
 
 	s.device.prph.DiscoverCharacteristics(cbuuids, s.service)
 
+	// clear cache of characteristics
+	s.device.characteristics = make(map[UUID]*DeviceCharacteristic)
+
 	// wait on channel for characteristic discovery
 	select {
 	case <-s.device.charsChan:
@@ -75,6 +82,7 @@ func (s *DeviceService) DiscoverCharacteristics(uuids []UUID) ([]DeviceCharacter
 				characteristic: dchar,
 			}
 			chars = append(chars, char)
+			s.device.characteristics[char.UUID] = &char
 		}
 		return chars, nil
 	case <-time.NewTimer(10 * time.Second).C: