diff --git a/lib/usb_dfu.c b/lib/usb_dfu.c
index 2c324ca..3782a03 100644
--- a/lib/usb_dfu.c
+++ b/lib/usb_dfu.c
@@ -20,6 +20,7 @@
 #include <libopencm3/stm32/flash.h> // flash utilities
 #include <libopencm3/usb/usbd.h> // USB library
 #include <libopencm3/usb/dfu.h> // USB DFU library
+#include <libopencm3/usb/dwc/otg_fs.h> // additional USB definitions
 
 #include "global.h" // global utilities
 #include "usb_dfu.h" // USB DFU header and definitions
@@ -366,6 +367,8 @@ void usb_dfu_setup(void)
 	gpio_set_af(GPIOA, GPIO_AF10, GPIO11 | GPIO12); // set alternate function to USB
 	usb_device = usbd_init(&otgfs_usb_driver, &usb_dfu_device, &usb_dfu_configuration, usb_dfu_strings, LENGTH(usb_dfu_strings), usbd_control_buffer, sizeof(usbd_control_buffer)); // configure USB device
 	usbd_register_control_callback(usb_device, USB_REQ_TYPE_CLASS | USB_REQ_TYPE_INTERFACE, USB_REQ_TYPE_TYPE | USB_REQ_TYPE_RECIPIENT, usb_dfu_control_request); // set control request handling DFU operations
+	OTG_FS_GCCFG |= OTG_GCCFG_NOVBUSSENS | OTG_GCCFG_PWRDWN; // disable VBUS sensing
+	OTG_FS_GCCFG &= ~(OTG_GCCFG_VBUSBSEN | OTG_GCCFG_VBUSASEN); // force USB device mode
 }
 
 void usb_dfu_start(void)