diff --git a/src/main.cpp b/src/main.cpp
index b2573f0..9c1b138 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -505,7 +505,7 @@ int main(int argc, char **argv)
 	}
 
 	if (found != 0) {
-		if (args.index_chain == -1) {
+		if (args.index_chain < 0) {
 			for (size_t i = 0; i < found; i++) {
 				if (fpga_list.find(listDev[i]) != fpga_list.end()) {
 					index = i;
@@ -523,7 +523,7 @@ int main(int argc, char **argv)
 			}
 		} else {
 			index = args.index_chain;
-			if (index > found || index < 0) {
+			if (index > found) {
 				printError("wrong index for device in JTAG chain");
 				delete(jtag);
 				return EXIT_FAILURE;
diff --git a/src/spiFlash.cpp b/src/spiFlash.cpp
index ff8f0fc..66fd2c8 100644
--- a/src/spiFlash.cpp
+++ b/src/spiFlash.cpp
@@ -944,7 +944,7 @@ bool SPIFlash::set_quad_bit(bool set_quad)
 
 	/* Micron: enable 0, disable 1 */
 	if (_jedec_id == 0x20BA)
-		set_quad = ~set_quad;
+		set_quad = !set_quad;
 	if (set_quad) // set quad_bit when required
 		quad_bit = _flash_model->quad_mask;
 
@@ -962,8 +962,9 @@ bool SPIFlash::set_quad_bit(bool set_quad)
 	 */
 	switch (_flash_model->quad_register) {
 		case CONFR:
-			uint8_t status = read_status_reg();
-			reg_val = ((reg_val & 0xff) << 8) | status;
+			reg_val = ((reg_val & 0xff) << 8) | read_status_reg();
+			break;
+		default: /* -Wswitch */
 			break;
 	}
 
diff --git a/src/xilinx.cpp b/src/xilinx.cpp
index 7e5332d..aeedf20 100644
--- a/src/xilinx.cpp
+++ b/src/xilinx.cpp
@@ -850,19 +850,7 @@ void Xilinx::program_mem(ConfigBitstreamParser *bitfile)
 	}
 }
 
-static const uint32_t reverseByte(uint32_t in) {
-	uint8_t out [4];
-	for (int i = 0; i < 4; i++) {
-		uint8_t tmp = (in >> (i*8)) & 0xff;
-		out[i] = BitParser::reverseByte(tmp);
-	}
-	return ((((uint32_t)out[0]) << 24) |
-		(((uint32_t)out[1]) << 16) |
-		(((uint32_t)out[2]) <<  8) |
-		(((uint32_t)out[3]) <<  0));
-}
-
-static const uint32_t reverseWord(uint32_t in) {
+static uint32_t reverseWord(uint32_t in) {
 	uint32_t out = 0;
 	for (int i = 0; i < 32; i++) {
 		out <<= 1;
@@ -871,7 +859,7 @@ static const uint32_t reverseWord(uint32_t in) {
 	return out;
 }
 
-static const uint32_t char_array_to_word(uint8_t *in)
+static uint32_t char_array_to_word(uint8_t *in)
 {
 	return (((uint32_t)in[3] << 24) |
 		((uint32_t)in[2] << 16) |
@@ -1808,7 +1796,7 @@ void Xilinx::xc2c_init(uint32_t idcode)
 {
 	_fpga_family = XC2C_FAMILY;
 	std::string model = fpga_list[idcode].model;
-	int underscore_pos = model.find_first_of('_', 0);
+	size_t underscore_pos = model.find_first_of('_', 0);
 	if (underscore_pos == model.npos) {
 		underscore_pos = model.length();
 	}