diff --git a/src/libei-device.c b/src/libei-device.c
index 8de8c4f..527c20c 100644
--- a/src/libei-device.c
+++ b/src/libei-device.c
@@ -277,6 +277,8 @@ handle_msg_paused(struct ei_device *device)
 static struct brei_result *
 handle_msg_start_emulating(struct ei_device *device, uint32_t sequence)
 {
+	struct brei_result *result = NULL;
+
 	DISCONNECT_IF_SENDER_CONTEXT(device);
 
 	switch (device->state) {
@@ -284,22 +286,27 @@ handle_msg_start_emulating(struct ei_device *device, uint32_t sequence)
 	case EI_DEVICE_STATE_NEW:
 	case EI_DEVICE_STATE_PAUSED:
 	case EI_DEVICE_STATE_EMULATING:
+	case EI_DEVICE_STATE_REMOVED_FROM_SERVER:
+		result = brei_result_new(EI_CONNECTION_DISCONNECT_REASON_PROTOCOL,
+					 "Invalid device state %ud for a start_emulating event", device->state);
 		break;
 	case EI_DEVICE_STATE_RESUMED:
 		ei_queue_device_start_emulating_event(device, sequence);
 		device->state = EI_DEVICE_STATE_EMULATING;
 		break;
 	case EI_DEVICE_STATE_REMOVED_FROM_CLIENT:
-	case EI_DEVICE_STATE_REMOVED_FROM_SERVER:
+		/* race condition, that's fine */
 		break;
 	}
 
-	return NULL;
+	return result;
 }
 
 static struct brei_result *
 handle_msg_stop_emulating(struct ei_device *device)
 {
+	struct brei_result *result = NULL;
+
 	DISCONNECT_IF_SENDER_CONTEXT(device);
 
 	switch (device->state) {
@@ -307,17 +314,20 @@ handle_msg_stop_emulating(struct ei_device *device)
 	case EI_DEVICE_STATE_NEW:
 	case EI_DEVICE_STATE_PAUSED:
 	case EI_DEVICE_STATE_RESUMED:
+	case EI_DEVICE_STATE_REMOVED_FROM_SERVER:
+		result = brei_result_new(EI_CONNECTION_DISCONNECT_REASON_PROTOCOL,
+					 "Invalid device state %ud for a stop_emulating event", device->state);
 		break;
 	case EI_DEVICE_STATE_EMULATING:
 		ei_queue_device_stop_emulating_event(device);
 		device->state = EI_DEVICE_STATE_RESUMED;
 		break;
 	case EI_DEVICE_STATE_REMOVED_FROM_CLIENT:
-	case EI_DEVICE_STATE_REMOVED_FROM_SERVER:
+		/* race condition, that's fine */
 		break;
 	}
 
-	return NULL;
+	return result;
 }
 
 static struct brei_result *