diff --git a/flight/PiOS/STM32F10x/pios_sys.c b/flight/PiOS/STM32F10x/pios_sys.c
index bfa1075d4..7d141e001 100644
--- a/flight/PiOS/STM32F10x/pios_sys.c
+++ b/flight/PiOS/STM32F10x/pios_sys.c
@@ -138,7 +138,7 @@ int32_t PIOS_SYS_SerialNumberGet(char *str)
 	int i;
 
 	/* Stored in the so called "electronic signature" */
-	for(i=0; i<12; ++i) {
+	for(i=0; i<24; ++i) {
 		uint8_t b = MEM8(0x1ffff7e8 + (i/2));
 		if( !(i & 1) )
 		b >>= 4;
@@ -146,7 +146,7 @@ int32_t PIOS_SYS_SerialNumberGet(char *str)
 
 		str[i] = ((b > 9) ? ('A'-10) : '0') + b;
 	}
-	str[i] = 0;
+	str[i] = '\0';
 
 	/* No error */
 	return 0;
diff --git a/flight/PiOS/STM32F10x/pios_usb_hid.c b/flight/PiOS/STM32F10x/pios_usb_hid.c
index fc2d74782..4c2bc0b63 100644
--- a/flight/PiOS/STM32F10x/pios_usb_hid.c
+++ b/flight/PiOS/STM32F10x/pios_usb_hid.c
@@ -98,21 +98,10 @@ int32_t PIOS_USB_HID_Init(uint32_t mode)
 	RCC_APB1PeriphClockCmd(RCC_APB1Periph_USB, ENABLE);
 	
     /* Update the USB serial number from the chip */
-    uint8_t sn[40];
-    PIOS_SYS_SerialNumberGet((char *) sn);
-    /*    uint8_t len = 0;;
-     for(uint8_t i = 0, len = 2; sn[i] != '\0' && len < PIOS_HID_StringSerial[0]; ++i) 
-     {
-     PIOS_HID_StringSerial[len++] = sn[i];
-     PIOS_HID_StringSerial[len++] = 0;
-     }
-     while(len < PIOS_HID_StringSerial[0]) 
-     {
-     PIOS_HID_StringSerial[len++] = 0;
-     } */
-    for(uint8_t i = 0; i < 12; i++) 
-    {
-        PIOS_HID_StringSerial[2+i*2] = sn[i];
+    uint8_t sn[25];
+    PIOS_SYS_SerialNumberGet((char *) sn);    
+    for(uint8_t i = 0; sn[i] != '\0' && (2 * i) < PIOS_HID_StringSerial[0]; i ++) {
+        PIOS_HID_StringSerial[2+2*i] = sn[i];
     }
     
 	USB_Init();
diff --git a/flight/PiOS/STM32F10x/pios_usb_hid_desc.c b/flight/PiOS/STM32F10x/pios_usb_hid_desc.c
index b14884f0f..0bbd1312c 100644
--- a/flight/PiOS/STM32F10x/pios_usb_hid_desc.c
+++ b/flight/PiOS/STM32F10x/pios_usb_hid_desc.c
@@ -178,7 +178,11 @@ uint8_t PIOS_HID_StringSerial[PIOS_HID_SIZ_STRING_SERIAL] =
   {
     PIOS_HID_SIZ_STRING_SERIAL,           /* bLength */
     USB_STRING_DESCRIPTOR_TYPE,        /* bDescriptorType */
-    'S', 0, 'T', 0, 'M', 0,'3', 0,'2', 0, '1', 0, '\0', 0
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0,       
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0       
   };
 
 /******************* (C) COPYRIGHT 2010 STMicroelectronics *****END OF FILE****/
diff --git a/flight/PiOS/inc/pios_usb_hid_desc.h b/flight/PiOS/inc/pios_usb_hid_desc.h
index a40c214a6..4810c1274 100644
--- a/flight/PiOS/inc/pios_usb_hid_desc.h
+++ b/flight/PiOS/inc/pios_usb_hid_desc.h
@@ -38,7 +38,7 @@
 #define PIOS_HID_SIZ_STRING_LANGID             4
 #define PIOS_HID_SIZ_STRING_VENDOR             28
 #define PIOS_HID_SIZ_STRING_PRODUCT            20
-#define PIOS_HID_SIZ_STRING_SERIAL             26
+#define PIOS_HID_SIZ_STRING_SERIAL             52 /* 96 bits, 12 bytes, 24 characters, 48 in unicode */
 
 #define STANDARD_ENDPOINT_DESC_SIZE             0x09