diff --git a/src/libeis-device.c b/src/libeis-device.c
index e07441b..18a5927 100644
--- a/src/libeis-device.c
+++ b/src/libeis-device.c
@@ -223,44 +223,55 @@ client_msg_release(struct eis_device *device)
 static struct brei_result *
 client_msg_start_emulating(struct eis_device *device, uint32_t sequence)
 {
+	struct brei_result *result = NULL;
+
 	DISCONNECT_IF_RECEIVER_CONTEXT(device);
 
 	switch (device->state) {
 	case EIS_DEVICE_STATE_DEAD:
 	case EIS_DEVICE_STATE_CLOSED_BY_CLIENT:
 	case EIS_DEVICE_STATE_NEW:
-	case EIS_DEVICE_STATE_PAUSED:
+	case EIS_DEVICE_STATE_EMULATING:
+		result = brei_result_new(EIS_CONNECTION_DISCONNECT_REASON_PROTOCOL,
+					 "Invalid device state %ud for a start_emulating event", device->state);
 		break;
 	case EIS_DEVICE_STATE_RESUMED:
 		eis_queue_device_start_emulating_event(device, sequence);
 		device->state = EIS_DEVICE_STATE_EMULATING;
 		break;
-	case EIS_DEVICE_STATE_EMULATING:
+	case EIS_DEVICE_STATE_PAUSED:
+		/* race condition, that's fine */
 		break;
 	}
 
-	return 0;
+	return result;
 }
 
 static struct brei_result *
 client_msg_stop_emulating(struct eis_device *device)
 {
+	struct brei_result *result = NULL;
+
 	DISCONNECT_IF_RECEIVER_CONTEXT(device);
 
 	switch (device->state) {
 	case EIS_DEVICE_STATE_DEAD:
 	case EIS_DEVICE_STATE_CLOSED_BY_CLIENT:
 	case EIS_DEVICE_STATE_NEW:
-	case EIS_DEVICE_STATE_PAUSED:
 	case EIS_DEVICE_STATE_RESUMED:
+		result = brei_result_new(EIS_CONNECTION_DISCONNECT_REASON_PROTOCOL,
+					 "Invalid device state %ud for a stop_emulating event", device->state);
 		break;
 	case EIS_DEVICE_STATE_EMULATING:
 		eis_queue_device_stop_emulating_event(device);
 		device->state = EIS_DEVICE_STATE_RESUMED;
 		break;
+	case EIS_DEVICE_STATE_PAUSED:
+		/* race condition, that's fine */
+		break;
 	}
 
-	return 0;
+	return result;
 }
 
 static struct brei_result *