diff --git a/hardware/arduino/avr/cores/arduino/PluggableUSB.h b/hardware/arduino/avr/cores/arduino/PluggableUSB.h
index d89040eb41d..23013eb7844 100644
--- a/hardware/arduino/avr/cores/arduino/PluggableUSB.h
+++ b/hardware/arduino/avr/cores/arduino/PluggableUSB.h
@@ -35,12 +35,6 @@ typedef struct __attribute__((packed))
   uint8_t *endpointType;
 } PUSBCallbacks;
 
-typedef struct
-{
-  u8 interface;
-  u8 firstEndpoint;
-} PUSBReturn;
-
 class PUSBListNode {
 public:
   PUSBListNode *next = NULL;
diff --git a/hardware/arduino/avr/libraries/HID/HID.cpp b/hardware/arduino/avr/libraries/HID/HID.cpp
index 8533f08ed40..3362886a36a 100644
--- a/hardware/arduino/avr/libraries/HID/HID.cpp
+++ b/hardware/arduino/avr/libraries/HID/HID.cpp
@@ -23,13 +23,13 @@
 
 HID_ HID;
 
-static u8 HID_ENDPOINT_INT;
+static uint8_t HID_ENDPOINT_INT;
 
 //================================================================================
 //================================================================================
 //	HID Interface
 
-static u8 HID_INTERFACE;
+static uint8_t HID_INTERFACE;
 
 HIDDescriptor _hidInterface;
 
@@ -40,10 +40,10 @@ static uint8_t modules_count = 0;
 //================================================================================
 //	Driver
 
-u8 _hid_protocol = 1;
-u8 _hid_idle = 1;
+uint8_t _hid_protocol = 1;
+uint8_t _hid_idle = 1;
 
-int HID_GetInterface(u8* interfaceNum)
+int HID_GetInterface(uint8_t* interfaceNum)
 {
 	interfaceNum[0] += 1;	// uses 1
 	_hidInterface =
@@ -85,19 +85,19 @@ void HID_::AppendDescriptor(HIDDescriptorListNode *node)
 	sizeof_hidReportDescriptor += (uint16_t)node->length;
 }
 
-void HID_::SendReport(u8 id, const void* data, int len)
+void HID_::SendReport(uint8_t id, const void* data, const uint16_t len)
 {
 	USB_Send(HID_TX, &id, 1);
 	USB_Send(HID_TX | TRANSFER_RELEASE,data,len);
 }
 
-bool HID_Setup(USBSetup& setup, u8 i)
+bool HID_Setup(USBSetup& setup, uint8_t i)
 {
 	if (HID_INTERFACE != i) {
 		return false;
 	} else {
-		u8 r = setup.bRequest;
-		u8 requestType = setup.bmRequestType;
+		uint8_t r = setup.bRequest;
+		uint8_t requestType = setup.bmRequestType;
 		if (REQUEST_DEVICETOHOST_CLASS_INTERFACE == requestType)
 		{
 			if (HID_GET_REPORT == r)
@@ -152,6 +152,7 @@ HID_::HID_(void)
 
 int HID_::begin(void)
 {
+	return 0;
 }
 
 #endif /* if defined(USBCON) */
diff --git a/hardware/arduino/avr/libraries/HID/HID.h b/hardware/arduino/avr/libraries/HID/HID.h
index f4ca7ae9a7b..e0572a6dc99 100644
--- a/hardware/arduino/avr/libraries/HID/HID.h
+++ b/hardware/arduino/avr/libraries/HID/HID.h
@@ -58,28 +58,28 @@ class HID_
 public:
   HID_(void);
   int begin(void);
-  void SendReport(uint8_t id, const void* data, int len);
+  void SendReport(uint8_t id, const void* data, const uint16_t len);
   void AppendDescriptor(HIDDescriptorListNode* node);
 };
 
 typedef struct
 {
-  u8 len;     // 9
-  u8 dtype;   // 0x21
-  u8 addr;
-  u8  versionL; // 0x101
-  u8  versionH; // 0x101
-  u8  country;
-  u8  desctype; // 0x22 report
-  u8  descLenL;
-  u8  descLenH;
+  uint8_t len;      // 9
+  uint8_t dtype;    // 0x21
+  uint8_t addr;
+  uint8_t versionL; // 0x101
+  uint8_t versionH; // 0x101
+  uint8_t country;
+  uint8_t desctype; // 0x22 report
+  uint8_t descLenL;
+  uint8_t descLenH;
 } HIDDescDescriptor;
 
 typedef struct 
 {
-  InterfaceDescriptor     hid;
-  HIDDescDescriptor     desc;
-  EndpointDescriptor      in;
+  InterfaceDescriptor hid;
+  HIDDescDescriptor   desc;
+  EndpointDescriptor  in;
 } HIDDescriptor;
 
 #define HID_TX HID_ENDPOINT_INT
diff --git a/hardware/arduino/sam/cores/arduino/USB/PluggableUSB.h b/hardware/arduino/sam/cores/arduino/USB/PluggableUSB.h
index 502da9ebcf0..75793fa32b4 100644
--- a/hardware/arduino/sam/cores/arduino/USB/PluggableUSB.h
+++ b/hardware/arduino/sam/cores/arduino/USB/PluggableUSB.h
@@ -35,12 +35,6 @@ typedef struct __attribute__((packed))
   uint32_t *endpointType;
 } PUSBCallbacks;
 
-typedef struct
-{
-  uint8_t interface;
-  uint8_t firstEndpoint;
-} PUSBReturn;
-
 class PUSBListNode {
 public:
   PUSBListNode *next = NULL;
diff --git a/hardware/arduino/sam/libraries/HID/HID.cpp b/hardware/arduino/sam/libraries/HID/HID.cpp
index b2a79423e35..06b08c843e9 100644
--- a/hardware/arduino/sam/libraries/HID/HID.cpp
+++ b/hardware/arduino/sam/libraries/HID/HID.cpp
@@ -92,13 +92,13 @@ void HID_::AppendDescriptor(HIDDescriptorListNode *node)
 	sizeof_hidReportDescriptor += node->length;
 }
 
-void HID_::SendReport(uint8_t id, const void* data, int len)
+void HID_::SendReport(uint8_t id, const void* data, const uint16_t len)
 {
 	uint8_t p[64];
 	const uint8_t *d = reinterpret_cast<const uint8_t *>(data);
 
 	p[0] = id;
-	for (uint32_t i=0; i<len; i++)
+	for (uint16_t i=0; i<len; i++)
 		p[i+1] = d[i];
 	USBD_Send(HID_TX, p, len+1);
 }
diff --git a/hardware/arduino/sam/libraries/HID/HID.h b/hardware/arduino/sam/libraries/HID/HID.h
index 10d89388dcb..382c7f24935 100644
--- a/hardware/arduino/sam/libraries/HID/HID.h
+++ b/hardware/arduino/sam/libraries/HID/HID.h
@@ -46,8 +46,9 @@ class HIDDescriptorListNode {
 public:
   HIDDescriptorListNode *next = NULL;
   HIDDescriptorListNode(const void *d, const uint16_t l) : data(d), length(l) { }
-  uint16_t length;
+
   const void* data;
+  const uint16_t length;
 };
 
 class HID_
@@ -55,7 +56,7 @@ class HID_
 public:
   HID_(void);
   int begin(void);
-  void SendReport(uint8_t id, const void* data, int len);
+  void SendReport(uint8_t id, const void* data, const uint16_t len);
   void AppendDescriptor(HIDDescriptorListNode* node);
 };