diff --git a/src/include/ipxe/device.h b/src/include/ipxe/device.h
index d81417e8..d4ba001b 100644
--- a/src/include/ipxe/device.h
+++ b/src/include/ipxe/device.h
@@ -72,7 +72,7 @@ struct device_description {
 /** A hardware device */
 struct device {
 	/** Name */
-	char name[32];
+	char name[40];
 	/** Driver name */
 	const char *driver_name;
 	/** Device description */
diff --git a/src/interface/hyperv/vmbus.c b/src/interface/hyperv/vmbus.c
index fd809dda..e269aee2 100644
--- a/src/interface/hyperv/vmbus.c
+++ b/src/interface/hyperv/vmbus.c
@@ -1121,6 +1121,7 @@ static int vmbus_probe_channels ( struct hv_hypervisor *hv,
 	const struct vmbus_message_header *header = &vmbus->message->header;
 	const struct vmbus_offer_channel *offer = &vmbus->message->offer;
 	const union uuid *type;
+	union uuid instance;
 	struct vmbus_driver *driver;
 	struct vmbus_device *vmdev;
 	struct vmbus_device *tmp;
@@ -1165,8 +1166,11 @@ static int vmbus_probe_channels ( struct hv_hypervisor *hv,
 				rc = -ENOMEM;
 				goto err_alloc_vmdev;
 			}
+			memcpy ( &instance, &offer->instance,
+				 sizeof ( instance ) );
+			uuid_mangle ( &instance );
 			snprintf ( vmdev->dev.name, sizeof ( vmdev->dev.name ),
-				   "vmbus:%02x", channel );
+				   "{%s}", uuid_ntoa ( &instance ) );
 			vmdev->dev.desc.bus_type = BUS_TYPE_HV;
 			INIT_LIST_HEAD ( &vmdev->dev.children );
 			list_add_tail ( &vmdev->dev.siblings,