diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/board.c b/libraries/AP_HAL_ChibiOS/hwdef/common/board.c
index b78cb68e9f..e1fffde4c9 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/board.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/board.c
@@ -16,6 +16,7 @@
  */
 
 #include "hal.h"
+#include "usbcfg.h"
 
 #if HAL_USE_PAL || defined(__DOXYGEN__)
 /**
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/stdio.c b/libraries/AP_HAL_ChibiOS/hwdef/common/stdio.c
index 55ec54116c..e823b5522d 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/stdio.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/stdio.c
@@ -28,6 +28,7 @@
 #include <hal.h>
 #include <memstreams.h>
 #include <chprintf.h>
+#include "stdio.h"
 
 int vsnprintf(char *str, size_t size, const char *fmt, va_list ap)
 {
@@ -116,6 +117,7 @@ int printf(const char *fmt, ...)
 int 
 scanf (const char *fmt, ...)
 {
+    (void)fmt;
     return 0;
 }
 /*
@@ -170,7 +172,7 @@ _atob (uint32_t *vp, char *p, int base)
   }
 
   if (base == 16 && (q = strchr (p, '.')) != 0) {
-    if (q - p > sizeof(tmp) - 1)
+      if ((unsigned)(q - p) > (unsigned)(sizeof(tmp) - 1))
       return (0);
 
     strncpy (tmp, p, q - p);
@@ -227,7 +229,7 @@ atob(uint32_t *vp, char *p, int base)
 }
 
 
-#if HAL_OS_FATFS_IO
+#if defined(HAL_OS_FATFS_IO) && HAL_OS_FATFS_IO
 /*
  *  vsscanf(buf,fmt,ap)
  */
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.c b/libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.c
index 989cb2ea36..27cb503c23 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.c
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.c
@@ -167,39 +167,6 @@ static const uint8_t vcom_string0[] = {
   USB_DESC_WORD(0x0409)                 /* wLANGID (U.S. English).          */
 };
 
-/*
- * Vendor string.
- */
-static const uint8_t vcom_string1[] = {
-  USB_DESC_BYTE(20),                    /* bLength.                         */
-  USB_DESC_BYTE(USB_DESCRIPTOR_STRING), /* bDescriptorType.                 */
-  'A', 0, 'r', 0, 'd', 0, 'u', 0, 'P', 0, 'i', 0, 'l', 0, 'o', 0,
-  't', 0
-};
-
-/*
- * Device Description string.
- */
-static const uint8_t vcom_string2[] = {
-  USB_DESC_BYTE(56),                    /* bLength.                         */
-  USB_DESC_BYTE(USB_DESCRIPTOR_STRING), /* bDescriptorType.                 */
-  'C', 0, 'h', 0, 'i', 0, 'b', 0, 'i', 0, 'O', 0, 'S', 0, '/', 0,
-  'R', 0, 'T', 0, ' ', 0, 'V', 0, 'i', 0, 'r', 0, 't', 0, 'u', 0,
-  'a', 0, 'l', 0, ' ', 0, 'C', 0, 'O', 0, 'M', 0, ' ', 0, 'P', 0,
-  'o', 0, 'r', 0, 't', 0
-};
-
-/*
- * Serial Number string.
- */
-static const uint8_t vcom_string3[] = {
-  USB_DESC_BYTE(8),                     /* bLength.                         */
-  USB_DESC_BYTE(USB_DESCRIPTOR_STRING), /* bDescriptorType.                 */
-  '0' + CH_KERNEL_MAJOR, 0,
-  '0' + CH_KERNEL_MINOR, 0,
-  '0' + CH_KERNEL_PATCH, 0
-};
-
 /*
  * Strings wrappers array. The strings are created dynamically to
  * allow them to be setup with apj_tool
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.h b/libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.h
index 35ff134d9b..3deb5d599e 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.h
+++ b/libraries/AP_HAL_ChibiOS/hwdef/common/usbcfg.h
@@ -33,4 +33,7 @@ extern const USBConfig usbcfg;
 extern SerialUSBConfig serusbcfg;
 extern SerialUSBDriver SDU1;
 #endif
-/** @} */
\ No newline at end of file
+
+void setup_usb_strings(void);
+
+/** @} */
diff --git a/libraries/AP_HAL_ChibiOS/system.cpp b/libraries/AP_HAL_ChibiOS/system.cpp
index da381374ce..23f5605f1c 100644
--- a/libraries/AP_HAL_ChibiOS/system.cpp
+++ b/libraries/AP_HAL_ChibiOS/system.cpp
@@ -38,10 +38,13 @@ typedef enum  {
 
 void *__dso_handle;
 
+void __cxa_pure_virtual(void);    
 void __cxa_pure_virtual() { while (1); } //TODO: Handle properly, maybe generate a traceback
 
+void NMI_Handler(void);
 void NMI_Handler(void) { while (1); }
 
+void HardFault_Handler(void);
 void HardFault_Handler(void) {
     //Copy to local variables (not pointers) to allow GDB "i loc" to directly show the info
     //Get thread context. Contains main registers including PC and LR
@@ -72,6 +75,7 @@ void HardFault_Handler(void) {
 
 void BusFault_Handler(void) __attribute__((alias("HardFault_Handler")));
 
+void UsageFault_Handler(void);
 void UsageFault_Handler(void) {
     //Copy to local variables (not pointers) to allow GDB "i loc" to directly show the info
     //Get thread context. Contains main registers including PC and LR
@@ -99,6 +103,7 @@ void UsageFault_Handler(void) {
     while(1) {}
 }
 
+void MemManage_Handler(void);
 void MemManage_Handler(void) {
     //Copy to local variables (not pointers) to allow GDB "i loc" to directly show the info
     //Get thread context. Contains main registers including PC and LR