diff --git a/examples/stm32/f1/other/usb_dfu/usbdfu.c b/examples/stm32/f1/other/usb_dfu/usbdfu.c
index 0211a47e..f30783f3 100644
--- a/examples/stm32/f1/other/usb_dfu/usbdfu.c
+++ b/examples/stm32/f1/other/usb_dfu/usbdfu.c
@@ -244,6 +244,8 @@ int main(void)
 	AFIO_MAPR |= AFIO_MAPR_SWJ_CFG_JTAG_OFF_SW_ON;
 	gpio_set_mode(GPIOA, GPIO_MODE_INPUT, 0, GPIO15);
 
+	rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_OTGFSEN);
+
 	usbd_init(&stm32f107_usb_driver, &dev, &config, usb_strings);
 	usbd_set_control_buffer_size(sizeof(usbd_control_buffer));
 	usbd_register_control_callback(
diff --git a/include/libopencm3/stm32/f1/desig.h b/include/libopencm3/stm32/f1/desig.h
index 74cfb353..6ceb6658 100644
--- a/include/libopencm3/stm32/f1/desig.h
+++ b/include/libopencm3/stm32/f1/desig.h
@@ -51,6 +51,15 @@ u16 desig_get_flash_size(void);
  */
 void desig_get_unique_id(u32 result[]);
 
+/**
+ * Read the full 96 bit unique identifier and return it as a
+ * zero-terminated string
+ * @param string memory region to write the result to
+ 8 @param string_len the size of string in bytes
+ */
+void desig_get_unique_id_as_string(char *string,
+				   unsigned int string_len);
+
 END_DECLS
 
 #endif
diff --git a/include/libopencm3/usb/usbd.h b/include/libopencm3/usb/usbd.h
index e4b35785..8f685557 100644
--- a/include/libopencm3/usb/usbd.h
+++ b/include/libopencm3/usb/usbd.h
@@ -24,6 +24,13 @@
 
 BEGIN_DECLS
 
+
+enum usbd_request_return_codes {
+	USBD_REQ_NOTSUPP	= 0,
+	USBD_REQ_HANDLED	= 1,
+	USBD_REQ_NEXT_CALLBACK	= 2,
+};
+
 typedef struct _usbd_driver usbd_driver;
 extern const usbd_driver stm32f103_usb_driver;
 extern const usbd_driver stm32f107_usb_driver;
@@ -38,7 +45,7 @@ extern u8 usbd_control_buffer[];
 extern int usbd_init(const usbd_driver *driver,
 		     const struct usb_device_descriptor *dev,
                      const struct usb_config_descriptor *conf,
-		     const char **strings);
+		     const char **strings, int num_strings);
 extern void usbd_set_control_buffer_size(u16 size);
 
 extern void usbd_register_reset_callback(void (*callback)(void));
diff --git a/include/libopencm3/usb/usbstd.h b/include/libopencm3/usb/usbstd.h
index 8610fdbc..01fc7e3c 100644
--- a/include/libopencm3/usb/usbstd.h
+++ b/include/libopencm3/usb/usbstd.h
@@ -220,4 +220,7 @@ struct usb_iface_assoc_descriptor {
 #define USB_DT_INTERFACE_ASSOCIATION_SIZE \
 				sizeof(struct usb_iface_assoc_descriptor)
 
+enum usb_language_id {
+	USB_LANGID_ENGLISH_US = 0x409,
+};
 #endif
diff --git a/lib/stm32/f1/desig.c b/lib/stm32/f1/desig.c
index 7ae968e1..7f213fab 100644
--- a/lib/stm32/f1/desig.c
+++ b/lib/stm32/f1/desig.c
@@ -35,3 +35,25 @@ void desig_get_unique_id(u32 result[])
     result[1] = bits63_32;
     result[2] = bits31_16 << 16 | bits15_0;
 }
+
+void desig_get_unique_id_as_string(char *string,
+				   unsigned int string_len)
+{
+	int i, len;
+	u8 device_id[12];
+	static const char chars[] = "0123456789ABCDEF";
+
+	desig_get_unique_id((u32 *)device_id);
+
+	/* Each byte produces two characters */
+	len = (2 * sizeof(device_id) < string_len) ?
+		2 * sizeof(device_id) : string_len - 1;
+
+	for (i = 0; i < len; i += 2) {
+		string[i]     = chars[(device_id[i / 2] >> 0) & 0x0F];
+		string[i + 1] = chars[(device_id[i / 2] >> 4) & 0x0F];
+	}
+
+	string[len] = '\0';
+}
+
diff --git a/lib/usb/usb.c b/lib/usb/usb.c
index 1ebb6ec5..d5ec9800 100644
--- a/lib/usb/usb.c
+++ b/lib/usb/usb.c
@@ -45,12 +45,14 @@ u8 usbd_control_buffer[128] __attribute__((weak));
  */
 int usbd_init(const usbd_driver *driver,
 	      const struct usb_device_descriptor *dev,
-	      const struct usb_config_descriptor *conf, const char **strings)
+	      const struct usb_config_descriptor *conf,
+	      const char **strings, int num_strings)
 {
 	_usbd_device.driver = driver;
 	_usbd_device.desc = dev;
 	_usbd_device.config = conf;
 	_usbd_device.strings = strings;
+	_usbd_device.num_strings = num_strings;
 	_usbd_device.ctrl_buf = usbd_control_buffer;
 	_usbd_device.ctrl_buf_len = sizeof(usbd_control_buffer);
 
diff --git a/lib/usb/usb_control.c b/lib/usb/usb_control.c
index 3dd08578..b4ac57e9 100644
--- a/lib/usb/usb_control.c
+++ b/lib/usb/usb_control.c
@@ -102,7 +102,8 @@ static int usb_control_request_dispatch(struct usb_setup_data *req)
 			result = cb[i].cb(req, &control_state.ctrl_buf,
 					  &control_state.ctrl_len,
 					  &control_state.complete);
-			if (result)
+			if (result == USBD_REQ_HANDLED ||
+			    result == USBD_REQ_NOTSUPP)
 				return result;
 		}
 	}
diff --git a/lib/usb/usb_private.h b/lib/usb/usb_private.h
index a1e5e4c8..238f14f3 100644
--- a/lib/usb/usb_private.h
+++ b/lib/usb/usb_private.h
@@ -29,6 +29,7 @@ extern struct _usbd_device {
 	const struct usb_device_descriptor *desc;
 	const struct usb_config_descriptor *config;
 	const char **strings;
+	int num_strings;
 
 	u8 *ctrl_buf;  /**< Internal buffer used for control transfers */
 	u16 ctrl_buf_len;
diff --git a/lib/usb/usb_standard.c b/lib/usb/usb_standard.c
index 2d7c619e..08923d85 100644
--- a/lib/usb/usb_standard.c
+++ b/lib/usb/usb_standard.c
@@ -87,50 +87,74 @@ static u16 build_config_descriptor(u8 index, u8 *buf, u16 len)
 	return total;
 }
 
+static int usb_descriptor_type(u16 wValue)
+{
+	return wValue >> 8;
+}
+
+static int usb_descriptor_index(u16 wValue)
+{
+	return wValue & 0xFF;
+}
+
 static int usb_standard_get_descriptor(struct usb_setup_data *req,
 				       u8 **buf, u16 *len)
 {
-	int i;
+	int i, array_idx, descr_idx;
 	struct usb_string_descriptor *sd;
 
-	switch (req->wValue >> 8) {
+	descr_idx = usb_descriptor_index(req->wValue);
+
+	switch (usb_descriptor_type(req->wValue)) {
 	case USB_DT_DEVICE:
 		*buf = (u8 *) _usbd_device.desc;
 		*len = MIN(*len, _usbd_device.desc->bLength);
-		return 1;
+		return USBD_REQ_HANDLED;
 	case USB_DT_CONFIGURATION:
 		*buf = _usbd_device.ctrl_buf;
-		*len = build_config_descriptor(req->wValue & 0xff, *buf, *len);
-		return 1;
+		*len = build_config_descriptor(descr_idx, *buf, *len);
+		return USBD_REQ_HANDLED;
 	case USB_DT_STRING:
 		sd = (struct usb_string_descriptor *)_usbd_device.ctrl_buf;
 
-		if (!_usbd_device.strings)
-			return 0; /* Device doesn't support strings. */
+		if (descr_idx == 0) {
+			/* Send sane Language ID descriptor... */
+			sd->wData[0] = USB_LANGID_ENGLISH_US;
+			sd->bLength = sizeof(sd->bLength) + sizeof(sd->bDescriptorType) 
+				+ sizeof(sd->wData[0]);
 
-		/* Check that string index is in range. */
-		for (i = 0; i <= (req->wValue & 0xff); i++)
-			if (_usbd_device.strings[i] == NULL)
-				return 0;
+			*len = MIN(*len, sd->bLength);
+		} else {
+			array_idx = descr_idx - 1;
+
+			if (!_usbd_device.strings)
+				return USBD_REQ_NOTSUPP; /* Device doesn't support strings. */
+			/* Check that string index is in range. */
+			if (array_idx >= _usbd_device.num_strings)
+				return USBD_REQ_NOTSUPP;
+
+			/* Strings with Language ID differnet from
+			 * USB_LANGID_ENGLISH_US are not supported */
+			if (req->wIndex != USB_LANGID_ENGLISH_US)
+				return USBD_REQ_NOTSUPP;
+
+			/* Ths string is returned as UTF16, hence the multiplication */
+			sd->bLength = strlen(_usbd_device.strings[array_idx]) * 2 +
+				sizeof(sd->bLength) + sizeof(sd->bDescriptorType);
+
+			*len = MIN(*len, sd->bLength);
+
+			for (i = 0; i < (*len / 2) - 1; i++)
+				sd->wData[i] =
+					_usbd_device.strings[array_idx][i];
+		}
 
-		sd->bLength = strlen(_usbd_device.strings[req->wValue & 0xff])
-				* 2 + 2;
 		sd->bDescriptorType = USB_DT_STRING;
-
 		*buf = (u8 *)sd;
-		*len = MIN(*len, sd->bLength);
 
-		for (i = 0; i < (*len / 2) - 1; i++)
-			sd->wData[i] =
-			    _usbd_device.strings[req->wValue & 0xff][i];
-
-		/* Send sane Language ID descriptor... */
-		if ((req->wValue & 0xff) == 0)
-			sd->wData[0] = 0x409;
-
-		return 1;
+		return USBD_REQ_HANDLED;
 	}
-	return 0;
+	return USBD_REQ_NOTSUPP;
 }
 
 static int usb_standard_set_address(struct usb_setup_data *req, u8 **buf,