diff --git a/spi.c b/spi.c
index f02f091..77cfb1e 100644
--- a/spi.c
+++ b/spi.c
@@ -97,9 +97,9 @@
 	return result;
 }
 
-int default_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len)
+int default_spi_read(struct flashchip *flash, uint8_t *buf, unsigned int start, unsigned int len)
 {
-	int max_data = spi_programmer->max_data_read;
+	unsigned int max_data = spi_programmer->max_data_read;
 	if (max_data == MAX_DATA_UNSPECIFIED) {
 		msg_perr("%s called, but SPI read chunk size not defined "
 			 "on this hardware. Please report a bug at "
@@ -109,9 +109,9 @@
 	return spi_read_chunked(flash, buf, start, len, max_data);
 }
 
-int default_spi_write_256(struct flashchip *flash, uint8_t *buf, int start, int len)
+int default_spi_write_256(struct flashchip *flash, uint8_t *buf, unsigned int start, unsigned int len)
 {
-	int max_data = spi_programmer->max_data_write;
+	unsigned int max_data = spi_programmer->max_data_write;
 	if (max_data == MAX_DATA_UNSPECIFIED) {
 		msg_perr("%s called, but SPI write chunk size not defined "
 			 "on this hardware. Please report a bug at "
@@ -121,7 +121,7 @@
 	return spi_write_chunked(flash, buf, start, len, max_data);
 }
 
-int spi_chip_read(struct flashchip *flash, uint8_t *buf, int start, int len)
+int spi_chip_read(struct flashchip *flash, uint8_t *buf, unsigned int start, unsigned int len)
 {
 	int addrbase = 0;
 	if (!spi_programmer->read) {
@@ -160,7 +160,7 @@
  * .write_256 = spi_chip_write_1
  */
 /* real chunksize is up to 256, logical chunksize is 256 */
-int spi_chip_write_256(struct flashchip *flash, uint8_t *buf, int start, int len)
+int spi_chip_write_256(struct flashchip *flash, uint8_t *buf, unsigned int start, unsigned int len)
 {
 	if (!spi_programmer->write_256) {
 		msg_perr("%s called, but SPI page write is unsupported on this "