diff --git a/ports/stm32/usb.c b/ports/stm32/usb.c
index 9427329e4d..bbb7310b80 100644
--- a/ports/stm32/usb.c
+++ b/ports/stm32/usb.c
@@ -57,6 +57,7 @@ mp_uint_t pyb_usb_flags = 0;
 STATIC USBD_HandleTypeDef hUSBDDevice;
 STATIC usbd_cdc_msc_hid_state_t usbd_cdc_msc_hid_state;
 STATIC usbd_cdc_itf_t usbd_cdc_itf;
+STATIC usbd_hid_itf_t usbd_hid_itf;
 pyb_usb_storage_medium_t pyb_usb_storage_medium = PYB_USB_STORAGE_MEDIUM_NONE;
 #endif
 
@@ -121,6 +122,7 @@ bool pyb_usb_dev_init(uint16_t vid, uint16_t pid, usb_device_mode_t mode, USBD_H
         usbd->pDesc = (USBD_DescriptorsTypeDef*)&USBD_Descriptors;
         usbd->pClass = &USBD_CDC_MSC_HID;
         usbd_cdc_msc_hid_state.cdc = &usbd_cdc_itf;
+        usbd_cdc_msc_hid_state.hid = &usbd_hid_itf;
         usbd->pClassData = &usbd_cdc_msc_hid_state;
 
         switch (pyb_usb_storage_medium) {
@@ -133,7 +135,6 @@ bool pyb_usb_dev_init(uint16_t vid, uint16_t pid, usb_device_mode_t mode, USBD_H
                 USBD_MSC_RegisterStorage(usbd, (USBD_StorageTypeDef*)&USBD_FLASH_STORAGE_fops);
                 break;
         }
-        USBD_HID_RegisterInterface(usbd, (USBD_HID_ItfTypeDef*)&USBD_HID_fops);
 
         // start the USB device
         USBD_LL_Init(usbd);
@@ -582,7 +583,7 @@ STATIC mp_obj_t pyb_usb_hid_recv(size_t n_args, const mp_obj_t *args, mp_map_t *
     mp_obj_t o_ret = pyb_buf_get_for_recv(vals[0].u_obj, &vstr);
 
     // receive the data
-    int ret = USBD_HID_Rx(&hUSBDDevice, (uint8_t*)vstr.buf, vstr.len, vals[1].u_int);
+    int ret = usbd_hid_rx(&usbd_hid_itf, vstr.len, (uint8_t*)vstr.buf, vals[1].u_int);
 
     // return the received data
     if (o_ret != MP_OBJ_NULL) {
@@ -642,7 +643,7 @@ STATIC mp_uint_t pyb_usb_hid_ioctl(mp_obj_t self_in, mp_uint_t request, mp_uint_
     if (request == MP_STREAM_POLL) {
         mp_uint_t flags = arg;
         ret = 0;
-        if ((flags & MP_STREAM_POLL_RD) && USBD_HID_RxNum() > 0) {
+        if ((flags & MP_STREAM_POLL_RD) && usbd_hid_rx_num(&usbd_hid_itf) > 0) {
             ret |= MP_STREAM_POLL_RD;
         }
         if ((flags & MP_STREAM_POLL_WR) && USBD_HID_CanSendReport(&hUSBDDevice)) {
diff --git a/ports/stm32/usbd_hid_interface.c b/ports/stm32/usbd_hid_interface.c
index 11b3a3acdc..badf0144bf 100644
--- a/ports/stm32/usbd_hid_interface.c
+++ b/ports/stm32/usbd_hid_interface.c
@@ -36,75 +36,47 @@
 
 #include <stdint.h>
 
-#include "usbd_cdc_msc_hid.h"
 #include "usbd_hid_interface.h"
 
 #include "py/obj.h"
 #include "irq.h"
 #include "usb.h"
 
-/* Private variables ---------------------------------------------------------*/
-
-static uint8_t buffer[2][HID_DATA_FS_MAX_PACKET_SIZE]; // pair of buffers to read individual packets into
-static int8_t current_read_buffer = 0; // which buffer to read from
-static uint32_t last_read_len = 0; // length of last read
-static int8_t current_write_buffer = 0; // which buffer to write to
-
-/* Private function prototypes -----------------------------------------------*/
-static int8_t HID_Itf_Init     (USBD_HandleTypeDef *pdev);
-static int8_t HID_Itf_Receive  (USBD_HandleTypeDef *pdev, uint8_t* pbuf, uint32_t Len);
-
-const USBD_HID_ItfTypeDef USBD_HID_fops = {
-    HID_Itf_Init,
-    HID_Itf_Receive
-};
-
-/**
-  * @brief  HID_Itf_Init
-  *         Initializes the HID media low layer
-  * @param  None
-  * @retval Result of the opeartion: USBD_OK if all operations are OK else USBD_FAIL
-  */
-static int8_t HID_Itf_Init(USBD_HandleTypeDef *pdev)
-{
-    current_read_buffer = 0;
-    last_read_len = 0;
-    current_write_buffer = 0;
-    USBD_HID_SetRxBuffer(pdev, buffer[current_write_buffer]);
-    return USBD_OK;
+void usbd_hid_init(usbd_hid_itf_t *hid, USBD_HandleTypeDef *pdev) {
+    hid->usb = pdev;
+    hid->current_read_buffer = 0;
+    hid->last_read_len = 0;
+    hid->current_write_buffer = 0;
+    USBD_HID_SetRxBuffer(pdev, hid->buffer[hid->current_write_buffer]);
 }
 
-/**
-  * @brief  HID_Itf_Receive
-  *         Data received over USB OUT endpoint is processed here.
-  * @param  Buf: Buffer of data received
-  * @param  Len: Number of data received (in bytes)
-  * @retval Result of the opeartion: USBD_OK if all operations are OK else USBD_FAIL
-  * @note   The buffer we are passed here is just UserRxBuffer, so we are
-  *         free to modify it.
-  */
-static int8_t HID_Itf_Receive(USBD_HandleTypeDef *pdev, uint8_t* Buf, uint32_t Len) {
-    current_write_buffer = !current_write_buffer;
-    last_read_len = Len;
+// Data received over USB OUT endpoint is processed here.
+// buf: Buffer of data received
+// len: Number of data received (in bytes)
+// Returns USBD_OK if all operations are OK else USBD_FAIL
+// The buffer we are passed here is just hid->buffer, so we are free to modify it.
+int8_t usbd_hid_receive(usbd_hid_itf_t *hid, size_t len, uint8_t *buf) {
+    hid->current_write_buffer = !hid->current_write_buffer;
+    hid->last_read_len = len;
     // initiate next USB packet transfer, to append to existing data in buffer
-    USBD_HID_SetRxBuffer(pdev, buffer[current_write_buffer]);
-    USBD_HID_ReceivePacket(pdev);
+    USBD_HID_SetRxBuffer(hid->usb, hid->buffer[hid->current_write_buffer]);
+    USBD_HID_ReceivePacket(hid->usb);
     // Set NAK to indicate we need to process read buffer
-    USBD_HID_SetNAK(pdev);
+    USBD_HID_SetNAK(hid->usb);
     return USBD_OK;
 }
 
 // Returns number of ready rx buffers.
-int USBD_HID_RxNum(void) {
-    return (current_read_buffer != current_write_buffer);
+int usbd_hid_rx_num(usbd_hid_itf_t *hid) {
+    return hid->current_read_buffer != hid->current_write_buffer;
 }
 
 // timout in milliseconds.
 // Returns number of bytes read from the device.
-int USBD_HID_Rx(USBD_HandleTypeDef *pdev, uint8_t *buf, uint32_t len, uint32_t timeout) {
+int usbd_hid_rx(usbd_hid_itf_t *hid, size_t len, uint8_t *buf, uint32_t timeout) {
     // Wait until we have buffer to read
     uint32_t start = HAL_GetTick();
-    while (current_read_buffer == current_write_buffer) {
+    while (hid->current_read_buffer == hid->current_write_buffer) {
         // Wraparound of tick is taken care of by 2's complement arithmetic.
         if (HAL_GetTick() - start >= timeout) {
             // timeout
@@ -118,17 +90,17 @@ int USBD_HID_Rx(USBD_HandleTypeDef *pdev, uint8_t *buf, uint32_t len, uint32_t t
     }
 
     // There is not enough space in buffer
-    if (len < last_read_len) {
+    if (len < hid->last_read_len) {
         return 0;
     }
 
     // Copy bytes from device to user buffer
-    memcpy(buf, buffer[current_read_buffer], last_read_len);
-    current_read_buffer = !current_read_buffer;
+    memcpy(buf, hid->buffer[hid->current_read_buffer], hid->last_read_len);
+    hid->current_read_buffer = !hid->current_read_buffer;
 
     // Clear NAK to indicate we are ready to read more data
-    USBD_HID_ClearNAK(pdev);
+    USBD_HID_ClearNAK(hid->usb);
 
     // Success, return number of bytes read
-    return last_read_len;
+    return hid->last_read_len;
 }
diff --git a/ports/stm32/usbd_hid_interface.h b/ports/stm32/usbd_hid_interface.h
index b2ff75fa13..3dc87de6bf 100644
--- a/ports/stm32/usbd_hid_interface.h
+++ b/ports/stm32/usbd_hid_interface.h
@@ -1,14 +1,21 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- */
-#ifndef MICROPY_INCLUDED_STMHAL_USBD_HID_INTERFACE_H
-#define MICROPY_INCLUDED_STMHAL_USBD_HID_INTERFACE_H
-
-#include "usbd_cdc_msc_hid.h"
-
-extern const USBD_HID_ItfTypeDef USBD_HID_fops;
-
-int USBD_HID_RxNum(void);
-int USBD_HID_Rx(USBD_HandleTypeDef *pdev, uint8_t *buf, uint32_t len, uint32_t timeout);
-
-#endif // MICROPY_INCLUDED_STMHAL_USBD_HID_INTERFACE_H
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ */
+#ifndef MICROPY_INCLUDED_STMHAL_USBD_HID_INTERFACE_H
+#define MICROPY_INCLUDED_STMHAL_USBD_HID_INTERFACE_H
+
+#include "usbd_cdc_msc_hid.h"
+
+typedef struct _usbd_hid_itf_t {
+    USBD_HandleTypeDef *usb; // the parent USB device
+
+    uint8_t buffer[2][HID_DATA_FS_MAX_PACKET_SIZE]; // pair of buffers to read individual packets into
+    int8_t current_read_buffer; // which buffer to read from
+    uint32_t last_read_len; // length of last read
+    int8_t current_write_buffer; // which buffer to write to
+} usbd_hid_itf_t;
+
+int usbd_hid_rx_num(usbd_hid_itf_t *hid);
+int usbd_hid_rx(usbd_hid_itf_t *hid, size_t len, uint8_t *buf, uint32_t timeout);
+
+#endif // MICROPY_INCLUDED_STMHAL_USBD_HID_INTERFACE_H
diff --git a/ports/stm32/usbdev/class/inc/usbd_cdc_msc_hid.h b/ports/stm32/usbdev/class/inc/usbd_cdc_msc_hid.h
index 5b2ffb4cf5..c7f9b15601 100644
--- a/ports/stm32/usbdev/class/inc/usbd_cdc_msc_hid.h
+++ b/ports/stm32/usbdev/class/inc/usbd_cdc_msc_hid.h
@@ -40,11 +40,6 @@ typedef struct {
   __IO uint32_t RxState;    
 } USBD_CDC_HandleTypeDef;
 
-typedef struct _USBD_HID_Itf {
-  int8_t (* Init)   (USBD_HandleTypeDef *pdev);
-  int8_t (* Receive)(USBD_HandleTypeDef *pdev, uint8_t *, uint32_t);
-} USBD_HID_ItfTypeDef;
-
 typedef struct _USBD_STORAGE {
   int8_t (* Init) (uint8_t lun);
   int8_t (* GetCapacity) (uint8_t lun, uint32_t *block_num, uint16_t *block_size);
@@ -109,7 +104,6 @@ uint8_t USBD_CDC_TransmitPacket  (USBD_HandleTypeDef *pdev);
 
 uint8_t USBD_MSC_RegisterStorage(USBD_HandleTypeDef *pdev, USBD_StorageTypeDef *fops);
 
-uint8_t USBD_HID_RegisterInterface(USBD_HandleTypeDef *pdev, USBD_HID_ItfTypeDef *fops);
 uint8_t USBD_HID_SetRxBuffer(USBD_HandleTypeDef *pdev, uint8_t *pbuff);
 uint8_t USBD_HID_ReceivePacket(USBD_HandleTypeDef *pdev);
 int USBD_HID_CanSendReport(USBD_HandleTypeDef *pdev);
@@ -123,4 +117,9 @@ void usbd_cdc_init(struct _usbd_cdc_itf_t *cdc, USBD_HandleTypeDef *pdev);
 int8_t usbd_cdc_control(struct _usbd_cdc_itf_t *cdc, uint8_t cmd, uint8_t* pbuf, uint16_t length);
 int8_t usbd_cdc_receive(struct _usbd_cdc_itf_t *cdc, uint8_t* Buf, uint32_t *Len);
 
+// These are provided externally to implement the HID interface
+struct _usbd_hid_itf_t;
+void usbd_hid_init(struct _usbd_hid_itf_t *hid, USBD_HandleTypeDef *pdev);
+int8_t usbd_hid_receive(struct _usbd_hid_itf_t *hid, size_t len, uint8_t *buf);
+
 #endif // _USB_CDC_MSC_CORE_H_
diff --git a/ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c b/ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c
index 38e5bcbc6b..d2daa3aee3 100644
--- a/ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c
+++ b/ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c
@@ -96,7 +96,6 @@ static uint8_t *hid_desc;
 static const uint8_t *hid_report_desc;
 
 static USBD_StorageTypeDef *MSC_fops;
-static USBD_HID_ItfTypeDef *HID_fops;
 
 static USBD_CDC_HandleTypeDef CDC_ClassData;
 static USBD_MSC_BOT_HandleTypeDef MSC_BOT_ClassData;
@@ -725,7 +724,7 @@ static uint8_t USBD_CDC_MSC_HID_Init(USBD_HandleTypeDef *pdev, uint8_t cfgidx) {
                        USBD_EP_TYPE_INTR,
                        mps_out);
 
-        HID_fops->Init(pdev);
+        usbd_hid_init(state->hid, pdev);
 
         // Prepare Out endpoint to receive next packet
         USBD_LL_PrepareReceive(pdev, hid_out_ep, HID_ClassData.RxBuffer, mps_out);
@@ -975,7 +974,7 @@ static uint8_t USBD_CDC_MSC_HID_DataOut(USBD_HandleTypeDef *pdev, uint8_t epnum)
         return USBD_OK;
     } else if ((usbd_mode & USBD_MODE_HID) && epnum == (hid_out_ep & 0x7f)) {
         HID_ClassData.RxLength = USBD_LL_GetRxDataSize(pdev, epnum);
-        HID_fops->Receive(pdev, HID_ClassData.RxBuffer, HID_ClassData.RxLength);
+        usbd_hid_receive(state->hid, HID_ClassData.RxLength, HID_ClassData.RxBuffer);
     }
 
     return USBD_OK;
@@ -1044,15 +1043,6 @@ uint8_t USBD_MSC_RegisterStorage(USBD_HandleTypeDef *pdev, USBD_StorageTypeDef *
     }
 }
 
-uint8_t USBD_HID_RegisterInterface(USBD_HandleTypeDef *pdev, USBD_HID_ItfTypeDef *fops) {
-    if (fops == NULL) {
-        return USBD_FAIL;
-    } else {
-        HID_fops = fops;
-        return USBD_OK;
-    }
-}
-
 uint8_t USBD_HID_SetRxBuffer(USBD_HandleTypeDef *pdev, uint8_t *pbuff) {
     HID_ClassData.RxBuffer = pbuff;
     return USBD_OK;