diff --git a/src/device/usbd_control.c b/src/device/usbd_control.c
index 8b1c92d81..7c970d605 100644
--- a/src/device/usbd_control.c
+++ b/src/device/usbd_control.c
@@ -49,14 +49,14 @@ typedef struct
   bool (*complete_cb) (uint8_t, tusb_control_request_t const *);
 } usbd_control_xfer_t;
 
-static usbd_control_xfer_t _control_state;
+static usbd_control_xfer_t _ctrl_xfer;
 
 CFG_TUSB_MEM_SECTION CFG_TUSB_MEM_ALIGN uint8_t _usbd_ctrl_buf[CFG_TUD_ENDPOINT0_SIZE];
 
 void usbd_control_reset (uint8_t rhport)
 {
   (void) rhport;
-  tu_varclr(&_control_state);
+  tu_varclr(&_ctrl_xfer);
 }
 
 bool tud_control_status(uint8_t rhport, tusb_control_request_t const * request)
@@ -68,14 +68,14 @@ bool tud_control_status(uint8_t rhport, tusb_control_request_t const * request)
 // Each transaction is up to endpoint0's max packet size
 static bool start_control_data_xact(uint8_t rhport)
 {
-  uint16_t const xact_len = tu_min16(_control_state.len - _control_state.total_transferred, CFG_TUD_ENDPOINT0_SIZE);
+  uint16_t const xact_len = tu_min16(_ctrl_xfer.len - _ctrl_xfer.total_transferred, CFG_TUD_ENDPOINT0_SIZE);
 
   uint8_t ep_addr = EDPT_CTRL_OUT;
 
-  if ( _control_state.request.bmRequestType_bit.direction == TUSB_DIR_IN )
+  if ( _ctrl_xfer.request.bmRequestType_bit.direction == TUSB_DIR_IN )
   {
     ep_addr = EDPT_CTRL_IN;
-    memcpy(_usbd_ctrl_buf, _control_state.buffer, xact_len);
+    memcpy(_usbd_ctrl_buf, _ctrl_xfer.buffer, xact_len);
   }
 
   return dcd_edpt_xfer(rhport, ep_addr, _usbd_ctrl_buf, xact_len);
@@ -84,15 +84,15 @@ static bool start_control_data_xact(uint8_t rhport)
 // TODO may find a better way
 void usbd_control_set_complete_callback( bool (*fp) (uint8_t, tusb_control_request_t const * ) )
 {
-  _control_state.complete_cb = fp;
+  _ctrl_xfer.complete_cb = fp;
 }
 
 bool tud_control_xfer(uint8_t rhport, tusb_control_request_t const * request, void* buffer, uint16_t len)
 {
-  _control_state.request = (*request);
-  _control_state.buffer = buffer;
-  _control_state.total_transferred = 0;
-  _control_state.len = tu_min16(len, request->wLength);
+  _ctrl_xfer.request = (*request);
+  _ctrl_xfer.buffer = buffer;
+  _ctrl_xfer.total_transferred = 0;
+  _ctrl_xfer.len = tu_min16(len, request->wLength);
 
   if ( len )
   {
@@ -115,32 +115,31 @@ bool usbd_control_xfer_cb (uint8_t rhport, uint8_t ep_addr, xfer_result_t result
   (void) result;
   (void) ep_addr;
 
-  if ( _control_state.request.bmRequestType_bit.direction == TUSB_DIR_OUT )
+  if ( _ctrl_xfer.request.bmRequestType_bit.direction == TUSB_DIR_OUT )
   {
-    TU_VERIFY(_control_state.buffer);
-    memcpy(_control_state.buffer, _usbd_ctrl_buf, xferred_bytes);
+    TU_VERIFY(_ctrl_xfer.buffer);
+    memcpy(_ctrl_xfer.buffer, _usbd_ctrl_buf, xferred_bytes);
   }
 
-  _control_state.total_transferred += xferred_bytes;
-  _control_state.buffer = ((uint8_t*)_control_state.buffer) + xferred_bytes;
-
-  if ( (_control_state.request.wLength == _control_state.total_transferred) || xferred_bytes < CFG_TUD_ENDPOINT0_SIZE )
+  _ctrl_xfer.total_transferred += xferred_bytes;
+  _ctrl_xfer.buffer = ((uint8_t*)_ctrl_xfer.buffer) + xferred_bytes;
 
+  if ( (_ctrl_xfer.request.wLength == _ctrl_xfer.total_transferred) || xferred_bytes < CFG_TUD_ENDPOINT0_SIZE )
   {
     // DATA stage is complete
     bool is_ok = true;
 
     // invoke complete callback if set
     // callback can still stall control in status phase e.g out data does not make sense
-    if ( _control_state.complete_cb )
+    if ( _ctrl_xfer.complete_cb )
     {
-      is_ok = _control_state.complete_cb(rhport, &_control_state.request);
+      is_ok = _ctrl_xfer.complete_cb(rhport, &_ctrl_xfer.request);
     }
 
     if ( is_ok )
     {
       // Send status
-      TU_ASSERT( tud_control_status(rhport, &_control_state.request) );
+      TU_ASSERT( tud_control_status(rhport, &_ctrl_xfer.request) );
     }else
     {
       // Stall both IN and OUT control endpoint