diff --git a/class/dfu/dfu.c b/class/dfu/dfu.c
index 0db5be7..5cf86b3 100644
--- a/class/dfu/dfu.c
+++ b/class/dfu/dfu.c
@@ -1,7 +1,7 @@
 #include "class/dfu/dfu.h"
 
-DFU_State dfu_state = DFU_STATE_dfuIDLE;
-DFU_Status dfu_status = DFU_STATUS_OK;
+DFU_State dfu_state;
+DFU_Status dfu_status;
 uint16_t dfu_poll_timeout;
 uint16_t dfu_block_offset;
 
diff --git a/samd/usb_samd.c b/samd/usb_samd.c
index 0f22c7a..2763c98 100644
--- a/samd/usb_samd.c
+++ b/samd/usb_samd.c
@@ -254,16 +254,3 @@ void USB_Handler() {
 	usb_cb_completion();
 }
 
-void* samd_serial_number_string_descriptor() {
-	char buf[27];
-
-	const unsigned char* id = (unsigned char*) 0x0080A00C;
-	for (int i=0; i<26; i++) {
-		unsigned idx = (i*5)/8;
-		unsigned pos = (i*5)%8;
-		unsigned val = ((id[idx] >> pos) | (id[idx+1] << (8-pos))) & ((1<<5)-1);
-		buf[i] = "0123456789ABCDFGHJKLMNPQRSTVWXYZ"[val];
-	}
-	buf[26] = 0;
-	return usb_string_to_descriptor(buf);
-}
diff --git a/samd/usb_samd.h b/samd/usb_samd.h
index 73e3b59..61e7dca 100644
--- a/samd/usb_samd.h
+++ b/samd/usb_samd.h
@@ -12,5 +12,3 @@ extern const uint8_t usb_num_endpoints;
 #define USB_ENDPOINTS(NUM_EP) \
 	const uint8_t usb_num_endpoints = (NUM_EP); \
 	UsbDeviceDescriptor usb_endpoints[(NUM_EP)+1];
-
-void* samd_serial_number_string_descriptor();