diff --git a/hidtest/test.c b/hidtest/test.c
index a694b8e64..bbea421e3 100644
--- a/hidtest/test.c
+++ b/hidtest/test.c
@@ -7,7 +7,7 @@
  8/22/2009
 
  Copyright 2009
- 
+
  This contents of this file may be used by anyone
  for any reason without any conditions and may be
  used as a starting point for your own applications
@@ -29,6 +29,9 @@
 
 int main(int argc, char* argv[])
 {
+	(void)argc;
+	(void)argv;
+
 	int res;
 	unsigned char buf[256];
 	#define MAX_STR 255
@@ -36,11 +39,6 @@ int main(int argc, char* argv[])
 	hid_device *handle;
 	int i;
 
-#ifdef WIN32
-	UNREFERENCED_PARAMETER(argc);
-	UNREFERENCED_PARAMETER(argv);
-#endif
-
 	struct hid_device_info *devs, *cur_dev;
 
 	printf("hidapi test/example tool. Compiled with hidapi version %s, runtime version %s.\n", HID_API_VERSION_STR, hid_version_str());
@@ -55,7 +53,7 @@ int main(int argc, char* argv[])
 		return -1;
 
 	devs = hid_enumerate(0x0, 0x0);
-	cur_dev = devs;	
+	cur_dev = devs;
 	while (cur_dev) {
 		printf("Device Found\n  type: %04hx %04hx\n  path: %s\n  serial_number: %ls", cur_dev->vendor_id, cur_dev->product_id, cur_dev->path, cur_dev->serial_number);
 		printf("\n");
@@ -73,7 +71,7 @@ int main(int argc, char* argv[])
 	memset(buf,0x00,sizeof(buf));
 	buf[0] = 0x01;
 	buf[1] = 0x81;
-	
+
 
 	// Open the device using the VID, PID,
 	// and optionally the Serial number.
@@ -115,7 +113,7 @@ int main(int argc, char* argv[])
 
 	// Set the hid_read() function to be non-blocking.
 	hid_set_nonblocking(handle, 1);
-	
+
 	// Try to read from the device. There should be no
 	// data here, but execution should not block.
 	res = hid_read(handle, buf, 17);
@@ -158,7 +156,7 @@ int main(int argc, char* argv[])
 		printf("Unable to write()\n");
 		printf("Error: %ls\n", hid_error(handle));
 	}
-	
+
 
 	// Request state (cmd 0x81). The first byte is the report number (0x1).
 	buf[0] = 0x1;
diff --git a/libusb/hid.c b/libusb/hid.c
index a82f9cca4..0b8aa1e7f 100644
--- a/libusb/hid.c
+++ b/libusb/hid.c
@@ -1098,18 +1098,21 @@ static void cleanup_mutex(void *param)
 
 int HID_API_EXPORT hid_read_timeout(hid_device *dev, unsigned char *data, size_t length, int milliseconds)
 {
-	int bytes_read = -1;
-
 #if 0
 	int transferred;
 	int res = libusb_interrupt_transfer(dev->device_handle, dev->input_endpoint, data, length, &transferred, 5000);
 	LOG("transferred: %d\n", transferred);
 	return transferred;
 #endif
+	/* by initialising this variable right here, GCC gives a compilation warning/error: */
+	/* error: variable ‘bytes_read’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered] */
+	int bytes_read; /* = -1; */
 
 	pthread_mutex_lock(&dev->mutex);
 	pthread_cleanup_push(&cleanup_mutex, dev);
 
+	bytes_read = -1;
+
 	/* There's an input report queued up. Return it. */
 	if (dev->input_reports) {
 		/* Return the first one */
@@ -1359,6 +1362,7 @@ int HID_API_EXPORT_CALL hid_get_indexed_string(hid_device *dev, int string_index
 
 HID_API_EXPORT const wchar_t * HID_API_CALL  hid_error(hid_device *dev)
 {
+	(void)dev;
 	return L"hid_error is not implemented yet";
 }
 
diff --git a/linux/hid.c b/linux/hid.c
index 15428c331..718541e5c 100644
--- a/linux/hid.c
+++ b/linux/hid.c
@@ -412,7 +412,7 @@ static int get_hid_report_descriptor_from_sysfs(const char *sysfs_path, struct h
  * strings pointed to by serial_number_utf8 and product_name_utf8 after use.
  */
 static int
-parse_uevent_info(const char *uevent, int *bus_type,
+parse_uevent_info(const char *uevent, unsigned *bus_type,
 	unsigned short *vendor_id, unsigned short *product_id,
 	char **serial_number_utf8, char **product_name_utf8)
 {
@@ -471,8 +471,8 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
 	struct udev_device *udev_dev, *parent, *hid_dev;
 	struct stat s;
 	int ret = -1;
-        char *serial_number_utf8 = NULL;
-        char *product_name_utf8 = NULL;
+	char *serial_number_utf8 = NULL;
+	char *product_name_utf8 = NULL;
 
 	/* Create the udev object */
 	udev = udev_new();
@@ -495,7 +495,7 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
 		if (hid_dev) {
 			unsigned short dev_vid;
 			unsigned short dev_pid;
-			int bus_type;
+			unsigned bus_type;
 			size_t retm;
 
 			ret = parse_uevent_info(
@@ -567,8 +567,8 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
 	}
 
 end:
-        free(serial_number_utf8);
-        free(product_name_utf8);
+	free(serial_number_utf8);
+	free(product_name_utf8);
 
 	udev_device_unref(udev_dev);
 	/* parent and hid_dev don't need to be (and can't be) unref'd.
@@ -647,7 +647,7 @@ struct hid_device_info  HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,
 		unsigned short dev_pid;
 		char *serial_number_utf8 = NULL;
 		char *product_name_utf8 = NULL;
-		int bus_type;
+		unsigned bus_type;
 		int result;
 		struct hidraw_report_descriptor report_desc;
 
@@ -1046,6 +1046,9 @@ int HID_API_EXPORT hid_get_feature_report(hid_device *dev, unsigned char *data,
 // Not supported by Linux HidRaw yet
 int HID_API_EXPORT HID_API_CALL hid_get_input_report(hid_device *dev, unsigned char *data, size_t length)
 {
+	(void)dev;
+	(void)data;
+	(void)length;
 	return -1;
 }
 
@@ -1082,6 +1085,10 @@ int HID_API_EXPORT_CALL hid_get_serial_number_string(hid_device *dev, wchar_t *s
 
 int HID_API_EXPORT_CALL hid_get_indexed_string(hid_device *dev, int string_index, wchar_t *string, size_t maxlen)
 {
+	(void)dev;
+	(void)string_index;
+	(void)string;
+	(void)maxlen;
 	return -1;
 }