diff --git a/src/Makefile b/src/Makefile
index 7a1f141..7ea7865 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -9,7 +9,7 @@ endif
 
 BUILDDATE := `date +"%Y%m%d"`
 
-CFLAGS += -Wall -Wextra -Wno-pointer-sign -Wno-char-subscripts\
+CFLAGS += -Wall -Wextra -Wno-char-subscripts\
 	-Wno-sign-compare \
 	-O2 -std=gnu99 -g3 -DBUILDDATE=\"$(BUILDDATE)\"\
 	-I. -Iinclude -Iplatforms/common -I$(PLATFORM_DIR) \
diff --git a/src/cortexm.c b/src/cortexm.c
index 71d0c6c..b3b657f 100644
--- a/src/cortexm.c
+++ b/src/cortexm.c
@@ -853,7 +853,8 @@ static int cortexm_hostio_request(target *t)
 		uint32_t pflag = flags[params[1] >> 1];
 		char filename[4];
 
-		target_mem_read_bytes(t, filename, params[0], sizeof(filename));
+		target_mem_read_bytes(t, (uint8_t *)filename,
+		                      params[0], sizeof(filename));
 		/* handle requests for console i/o */
 		if (!strcmp(filename, ":tt")) {
 			if (pflag == FILEIO_O_RDONLY)
diff --git a/src/gdb_main.c b/src/gdb_main.c
index 0c3dd77..ab4fc8a 100644
--- a/src/gdb_main.c
+++ b/src/gdb_main.c
@@ -41,7 +41,7 @@
 #define ERROR_IF_NO_TARGET()	\
 	if(!cur_target) { gdb_putpacketz("EFF"); break; }
 
-static unsigned char pbuf[BUF_SIZE];
+static char pbuf[BUF_SIZE];
 
 static target *cur_target;
 static target *last_target;
@@ -287,7 +287,7 @@ handle_q_string_reply(const char *str, const char *param)
 		return;
 	}
 	if (addr < strlen (str)) {
-		uint8_t reply[len+2];
+		char reply[len+2];
 		reply[0] = 'm';
 		strncpy (reply + 1, &str[addr], len);
 		if(len > strlen(&str[addr]))
@@ -305,7 +305,7 @@ handle_q_packet(char *packet, int len)
 	uint32_t addr, alen;
 
 	if(!strncmp(packet, "qRcmd,", 6)) {
-		unsigned char *data;
+		char *data;
 		int datalen;
 
 		/* calculate size and allocate buffer for command */
diff --git a/src/gdb_packet.c b/src/gdb_packet.c
index 4dc934f..fb3335e 100644
--- a/src/gdb_packet.c
+++ b/src/gdb_packet.c
@@ -29,8 +29,7 @@
 
 #include <stdarg.h>
 
-int
-gdb_getpacket(unsigned char *packet, int size)
+int gdb_getpacket(char *packet, int size)
 {
 	unsigned char c;
 	unsigned char csum;
@@ -89,7 +88,7 @@ gdb_getpacket(unsigned char *packet, int size)
 	return i;
 }
 
-void gdb_putpacket(unsigned char *packet, int size)
+void gdb_putpacket(const char *packet, int size)
 {
 	int i;
 	unsigned char csum;
@@ -130,7 +129,7 @@ void gdb_putpacket(unsigned char *packet, int size)
 	} while((gdb_if_getchar_to(2000) != '+') && (tries++ < 3));
 }
 
-void gdb_putpacket_f(const unsigned char *fmt, ...)
+void gdb_putpacket_f(const char *fmt, ...)
 {
 	va_list ap;
 	char *buf;
diff --git a/src/hex_utils.c b/src/hex_utils.c
index 45382ff..e18df58 100644
--- a/src/hex_utils.c
+++ b/src/hex_utils.c
@@ -24,15 +24,16 @@
 #include "general.h"
 #include "hex_utils.h"
 
-static char hexdigits[] = "0123456789abcdef";
+static const char hexdigits[] = "0123456789abcdef";
 
-char * hexify(char *hex, const unsigned char *buf, int size)
+char * hexify(char *hex, const void *buf, size_t size)
 {
 	char *tmp = hex;
+	const uint8_t *b = buf;
 
-	while(size--) {
-		*tmp++ = hexdigits[*buf >> 4];
-		*tmp++ = hexdigits[*buf++ & 0xF];
+	while (size--) {
+		*tmp++ = hexdigits[*b >> 4];
+		*tmp++ = hexdigits[*b++ & 0xF];
 	}
 	*tmp++ = 0;
 
@@ -49,11 +50,12 @@ static uint8_t unhex_digit(char hex)
 	return tmp;
 }
 
-char * unhexify(unsigned char *buf, const char *hex, int size)
+char * unhexify(void *buf, const char *hex, size_t size)
 {
-	while(size--) {
-		*buf = unhex_digit(*hex++) << 4;
-		*buf++ |= unhex_digit(*hex++);
+	uint8_t *b = buf;
+	while (size--) {
+		*b = unhex_digit(*hex++) << 4;
+		*b++ |= unhex_digit(*hex++);
 	}
 	return buf;
 }
diff --git a/src/include/gdb_packet.h b/src/include/gdb_packet.h
index 222b86d..aa1a654 100644
--- a/src/include/gdb_packet.h
+++ b/src/include/gdb_packet.h
@@ -21,10 +21,10 @@
 #ifndef __GDB_PACKET_H
 #define __GDB_PACKET_H
 
-int gdb_getpacket(unsigned char *packet, int size);
-void gdb_putpacket(unsigned char *packet, int size);
+int gdb_getpacket(char *packet, int size);
+void gdb_putpacket(const char *packet, int size);
 #define gdb_putpacketz(packet) gdb_putpacket((packet), strlen(packet))
-void gdb_putpacket_f(const unsigned char *packet, ...);
+void gdb_putpacket_f(const char *packet, ...);
 
 void gdb_out(const char *buf);
 void gdb_outf(const char *fmt, ...);
diff --git a/src/include/hex_utils.h b/src/include/hex_utils.h
index 3aa210b..8a0d092 100644
--- a/src/include/hex_utils.h
+++ b/src/include/hex_utils.h
@@ -21,9 +21,8 @@
 #ifndef __HEX_UTILS_H
 #define __HEX_UTILS_H
 
-char * hexify(char *hex, const unsigned char *buf, int size);
-
-char * unhexify(unsigned char *buf, const char *hex, int size);
+char * hexify(char *hex, const void *buf, size_t size);
+char * unhexify(void *buf, const char *hex, size_t size);
 
 #endif
 
diff --git a/src/jtag_scan.c b/src/jtag_scan.c
index 208a1db..c4e80cf 100644
--- a/src/jtag_scan.c
+++ b/src/jtag_scan.c
@@ -74,7 +74,7 @@ static struct jtag_dev_descr_s {
 };
 
 /* bucket of ones for don't care TDI */
-static const char ones[] = "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF";
+static const uint8_t ones[] = "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF";
 
 /* Scan JTAG chain for devices, store IR length and IDCODE (if present).
  * Reset TAP state machine.
diff --git a/src/platforms/libftdi/jtagtap.c b/src/platforms/libftdi/jtagtap.c
index c9bc876..c416892 100644
--- a/src/platforms/libftdi/jtagtap.c
+++ b/src/platforms/libftdi/jtagtap.c
@@ -97,7 +97,7 @@ jtagtap_tms_seq(uint32_t MS, int ticks)
 void
 jtagtap_tdi_seq(const uint8_t final_tms, const uint8_t *DI, int ticks)
 {
-	char *tmp;
+	uint8_t *tmp;
 	int index = 0;
 	int rticks;
 
diff --git a/src/platforms/libftdi/swdptap.c b/src/platforms/libftdi/swdptap.c
index eb6e65e..6aafa7d 100644
--- a/src/platforms/libftdi/swdptap.c
+++ b/src/platforms/libftdi/swdptap.c
@@ -45,7 +45,7 @@ int swdptap_init(void)
 		abort();
 	}
 
-	assert(ftdi_write_data(ftdic, "\xAB\xA8", 2) == 2);
+	assert(ftdi_write_data(ftdic, (void*)"\xAB\xA8", 2) == 2);
 
 	/* This must be investigated in more detail.
 	 * As described in STM32 Reference Manual... */
@@ -70,7 +70,6 @@ static void swdptap_turnaround(uint8_t dir)
 {
 	static uint8_t olddir = 0;
 
-	/*DEBUG("%s", dir ? "\n-> ":"\n<- ");*/
 	platform_buffer_flush();
 
 	if(dir == olddir) return;
@@ -80,7 +79,7 @@ static void swdptap_turnaround(uint8_t dir)
 		assert(ftdi_set_bitmode(ftdic, 0xA3, BITMODE_BITBANG) == 0);
 
 	/* One clock cycle */
-	ftdi_write_data(ftdic, "\xAB\xA8", 2);
+	ftdi_write_data(ftdic, (void *)"\xAB\xA8", 2);
 
 	if(!dir) /* SWDIO goes to output */
 		assert(ftdi_set_bitmode(ftdic, 0xAB, BITMODE_BITBANG) == 0);
@@ -90,12 +89,9 @@ static uint8_t swdptap_bit_in(void)
 {
 	uint8_t ret;
 
-	//ftdi_read_data(ftdic, &ret, 1);
 	ftdi_read_pins(ftdic, &ret);
 	ret &= 0x08;
-	ftdi_write_data(ftdic, "\xA1\xA0", 2);
-
-	//DEBUG("%d", ret?1:0);
+	ftdi_write_data(ftdic, (void *)"\xA1\xA0", 2);
 
 	return ret;
 }
@@ -104,13 +100,10 @@ static void swdptap_bit_out(uint8_t val)
 {
 	uint8_t buf[3] = "\xA0\xA1\xA0";
 
-	//DEBUG("%d", val);
-
 	if(val) {
 		for(int i = 0; i < 3; i++)
 			buf[i] |= 0x08;
 	}
-	//ftdi_write_data(ftdic, buf, 3);
 	platform_buffer_write(buf, 3);
 }