diff --git a/core/usb/device.h b/core/usb/device.h
index 832db364..20b64902 100644
--- a/core/usb/device.h
+++ b/core/usb/device.h
@@ -51,7 +51,7 @@ typedef struct usb_transfer_info {
     uint16_t length, max_pkt_size;
     usb_transfer_status_t status : 8;
     uint8_t address : 7, : 1, endpoint : 4;
-    usb_transfer_type_t type : 3;
+    uint8_t type : 3; /* usb_transfer_type_t */
     bool direction : 1;
 } usb_transfer_info_t;
 
@@ -72,7 +72,7 @@ typedef struct usb_event {
     usb_progress_handler_t *progress_handler;
     void *progress_context, *context;
     bool host : 1;
-    usb_speed_t speed : 2;
+    uint8_t speed : 2; /* usb_speed_t */
     usb_event_type_t type;
     union {
         usb_init_info_t init;
diff --git a/core/usb/physical.c b/core/usb/physical.c
index ffc42df9..876a9402 100644
--- a/core/usb/physical.c
+++ b/core/usb/physical.c
@@ -114,16 +114,18 @@ struct hub {
     port_t ports[];
 };
 
+enum device_state {
+    DEVICE_STATE_ATTACHED,
+    DEVICE_STATE_POWERED,
+    DEVICE_STATE_DEFAULT_OR_ADDRESS,
+    DEVICE_STATE_CONFIGURED,
+};
+
 struct device {
     node_t node;
     libusb_device_handle *handle;
     endpoint_t endpoints[0x20];
-    enum device_state {
-        DEVICE_STATE_ATTACHED,
-        DEVICE_STATE_POWERED,
-        DEVICE_STATE_DEFAULT_OR_ADDRESS,
-        DEVICE_STATE_CONFIGURED,
-    } state : 2;
+    uint8_t state : 2; /* enum device_state */
     uint8_t address : 7, numPorts : 7;
     hub_t hub;
 };