diff --git a/src/anlogicCable.cpp b/src/anlogicCable.cpp
index 7efc564..795eac3 100644
--- a/src/anlogicCable.cpp
+++ b/src/anlogicCable.cpp
@@ -138,7 +138,7 @@ int AnlogicCable::setClkFreq(uint32_t clkHZ)
 	return clkHZ;
 }
 
-int AnlogicCable::writeTMS(uint8_t *tms, int len, bool flush_buffer)
+int AnlogicCable::writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer)
 {
 	(void) flush_buffer;
 
diff --git a/src/anlogicCable.hpp b/src/anlogicCable.hpp
index 8bd702f..00f7f89 100644
--- a/src/anlogicCable.hpp
+++ b/src/anlogicCable.hpp
@@ -25,7 +25,7 @@ class AnlogicCable : public JtagInterface {
 	int setClkFreq(uint32_t clkHZ) override;
 
 	/* TMS */
-	int writeTMS(uint8_t *tms, int len, bool flush_buffer) override;
+	int writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer) override;
 	/* TDI */
 	int writeTDI(uint8_t *tx, uint8_t *rx, uint32_t len, bool end) override;
 	/* clk */
diff --git a/src/cmsisDAP.cpp b/src/cmsisDAP.cpp
index 7a75b03..5b42abc 100644
--- a/src/cmsisDAP.cpp
+++ b/src/cmsisDAP.cpp
@@ -291,7 +291,7 @@ int CmsisDAP::setClkFreq(uint32_t clkHZ)
  * flush the buffer
  * tms states are written only if max or if flush_buffer set
  */
-int CmsisDAP::writeTMS(uint8_t *tms, int len, bool flush_buffer)
+int CmsisDAP::writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer)
 {
 	/* nothing to send
 	 * check if the buffer must be flushed
@@ -303,7 +303,7 @@ int CmsisDAP::writeTMS(uint8_t *tms, int len, bool flush_buffer)
 	}
 
 	/* fill buffer with tms states */
-	for (int pos = 0; pos < len; pos++) {
+	for (uint32_t pos = 0; pos < len; pos++) {
 		/* max tms states allowed by CMSIS-DAP -> flush */
 		if (_num_tms == 256) {
 			if (flush() < 0) {
@@ -481,6 +481,8 @@ int CmsisDAP::flush()
 int CmsisDAP::xfer(uint8_t instruction, int tx_len,
 		uint8_t *rx_buff, int rx_len)
 {
+	(void)tx_len;
+
 	_ll_buffer[0] = 0;
 	_ll_buffer[1] = instruction;
 
@@ -516,6 +518,8 @@ int CmsisDAP::xfer(uint8_t instruction, int tx_len,
  */
 int CmsisDAP::xfer(int tx_len, uint8_t *rx_buff, int rx_len)
 {
+	(void)tx_len;
+
 	_ll_buffer[0] = 0;
 
 	int ret = hid_write(_dev, _ll_buffer, 65);
diff --git a/src/cmsisDAP.hpp b/src/cmsisDAP.hpp
index e981119..5dee1d7 100644
--- a/src/cmsisDAP.hpp
+++ b/src/cmsisDAP.hpp
@@ -42,7 +42,7 @@ class CmsisDAP: public JtagInterface {
 		 * \param[in] flush_buffer: force buffer to be send or not
 		 * \return <= 0 if something wrong, len otherwise
 		 */
-		int writeTMS(uint8_t *tms, int len, bool flush_buffer) override;
+		int writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer) override;
 
 		/*!
 		 * \brief write and read len bits with optional tms set to 1 if end
diff --git a/src/dirtyJtag.cpp b/src/dirtyJtag.cpp
index 1774b79..71d3e6b 100644
--- a/src/dirtyJtag.cpp
+++ b/src/dirtyJtag.cpp
@@ -167,7 +167,7 @@ int DirtyJtag::setClkFreq(uint32_t clkHZ)
 	return clkHZ;
 }
 
-int DirtyJtag::writeTMS(uint8_t *tms, int len, bool flush_buffer)
+int DirtyJtag::writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer)
 {
 	(void) flush_buffer;
 	int actual_length;
@@ -178,7 +178,7 @@ int DirtyJtag::writeTMS(uint8_t *tms, int len, bool flush_buffer)
 	uint8_t mask = SIG_TCK | SIG_TMS;
 	uint8_t buf[64];
 	u_int buffer_idx = 0;
-	for (int i = 0; i < len; i++)
+	for (uint32_t i = 0; i < len; i++)
 	{
 		uint8_t val = (tms[i >> 3] & (1 << (i & 0x07))) ? SIG_TMS : 0;
 		buf[buffer_idx++] = CMD_SETSIG;
diff --git a/src/dirtyJtag.hpp b/src/dirtyJtag.hpp
index 13ccf89..11d304e 100644
--- a/src/dirtyJtag.hpp
+++ b/src/dirtyJtag.hpp
@@ -25,7 +25,7 @@ class DirtyJtag : public JtagInterface {
 	int setClkFreq(uint32_t clkHZ) override;
 
 	/* TMS */
-	int writeTMS(uint8_t *tms, int len, bool flush_buffer) override;
+	int writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer) override;
 	/* TDI */
 	int writeTDI(uint8_t *tx, uint8_t *rx, uint32_t len, bool end) override;
 	/* clk */
diff --git a/src/ftdiJtagBitbang.cpp b/src/ftdiJtagBitbang.cpp
index aa79c6b..ab48e07 100644
--- a/src/ftdiJtagBitbang.cpp
+++ b/src/ftdiJtagBitbang.cpp
@@ -104,7 +104,7 @@ int FtdiJtagBitBang::setBitmode(uint8_t mode)
 	return ret;
 }
 
-int FtdiJtagBitBang::writeTMS(uint8_t *tms, int len, bool flush_buffer)
+int FtdiJtagBitBang::writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer)
 {
 	int ret;
 
@@ -127,7 +127,7 @@ int FtdiJtagBitBang::writeTMS(uint8_t *tms, int len, bool flush_buffer)
 	}
 
 	/* fill buffer to reduce USB transaction */
-	for (int i = 0; i < len; i++) {
+	for (uint32_t i = 0; i < len; i++) {
 		_curr_tms = ((tms[i >> 3] & (1 << (i & 0x07)))? _tms_pin : 0);
 		uint8_t val = _tdi_pin | _curr_tms;
 		_buffer[_num++] = val;
diff --git a/src/ftdiJtagBitbang.hpp b/src/ftdiJtagBitbang.hpp
index 1ef2a90..018d3dd 100644
--- a/src/ftdiJtagBitbang.hpp
+++ b/src/ftdiJtagBitbang.hpp
@@ -31,7 +31,7 @@ class FtdiJtagBitBang : public JtagInterface, private FTDIpp_MPSSE {
 	int setClkFreq(uint32_t clkHZ) override;
 
 	/* TMS */
-	int writeTMS(uint8_t *tms, int len, bool flush_buffer) override;
+	int writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer) override;
 
 	/* TDI */
 	int writeTDI(uint8_t *tx, uint8_t *rx, uint32_t len, bool end) override;
diff --git a/src/ftdiJtagMPSSE.cpp b/src/ftdiJtagMPSSE.cpp
index 2a34d0e..a875372 100644
--- a/src/ftdiJtagMPSSE.cpp
+++ b/src/ftdiJtagMPSSE.cpp
@@ -103,7 +103,7 @@ void FtdiJtagMPSSE::config_edge()
 	}
 }
 
-int FtdiJtagMPSSE::writeTMS(uint8_t *tms, int len, bool flush_buffer)
+int FtdiJtagMPSSE::writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer)
 {
 	(void) flush_buffer;
 	display("%s %d %d\n", __func__, len, (len/8)+1);
diff --git a/src/ftdiJtagMPSSE.hpp b/src/ftdiJtagMPSSE.hpp
index efbecc6..7392640 100644
--- a/src/ftdiJtagMPSSE.hpp
+++ b/src/ftdiJtagMPSSE.hpp
@@ -31,7 +31,7 @@ class FtdiJtagMPSSE : public JtagInterface, private FTDIpp_MPSSE {
 	uint32_t getClkFreq() override {return FTDIpp_MPSSE::getClkFreq();}
 
 	/* TMS */
-	int writeTMS(uint8_t *tms, int len, bool flush_buffer) override;
+	int writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer) override;
 	/* clock */
 	int toggleClk(uint8_t tms, uint8_t tdi, uint32_t clk_len) override;
 	/* TDI */
diff --git a/src/jtagInterface.hpp b/src/jtagInterface.hpp
index ba5d38c..37a3a63 100644
--- a/src/jtagInterface.hpp
+++ b/src/jtagInterface.hpp
@@ -29,7 +29,7 @@ class JtagInterface {
 	 * \param len: number of bit to send
 	 * \return number of bit send/received
 	 */
-	virtual int writeTMS(uint8_t *tms, int len, bool flush_buffer) = 0;
+	virtual int writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer) = 0;
 
 	/*!
 	 * \brief send TDI bits (mainly in shift DR/IR state)
diff --git a/src/usbBlaster.cpp b/src/usbBlaster.cpp
index c80a794..17ee633 100644
--- a/src/usbBlaster.cpp
+++ b/src/usbBlaster.cpp
@@ -90,7 +90,7 @@ uint32_t UsbBlaster::getClkFreq()
 	return ll_driver->getClkFreq();
 }
 
-int UsbBlaster::writeTMS(uint8_t *tms, int len, bool flush_buffer)
+int UsbBlaster::writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer)
 {
 	int ret;
 
@@ -113,7 +113,7 @@ int UsbBlaster::writeTMS(uint8_t *tms, int len, bool flush_buffer)
 	}
 
 	/* fill buffer to reduce USB transaction */
-	for (int i = 0; i < len; i++) {
+	for (uint32_t i = 0; i < len; i++) {
 		_curr_tms = ((tms[i >> 3] & (1 << (i & 0x07)))? _tms_pin : 0);
 		uint8_t val = DEFAULT | DO_WRITE | DO_BITBB | _tdi_pin | _curr_tms;
 		_in_buf[_nb_bit++] = val;
diff --git a/src/usbBlaster.hpp b/src/usbBlaster.hpp
index a8204ba..69ba723 100644
--- a/src/usbBlaster.hpp
+++ b/src/usbBlaster.hpp
@@ -54,7 +54,7 @@ class UsbBlaster : public JtagInterface {
 	 * \param flush_buffer force flushing the buffer
 	 * \return number of state written
 	 * */
-	int writeTMS(uint8_t *tms, int len, bool flush_buffer) override;
+	int writeTMS(uint8_t *tms, uint32_t len, bool flush_buffer) override;
 
 	/* TDI */
 	int writeTDI(uint8_t *tx, uint8_t *rx, uint32_t len, bool end) override;