diff --git a/programmer.h b/programmer.h
index 73b94c1..c92713a 100644
--- a/programmer.h
+++ b/programmer.h
@@ -556,23 +556,23 @@
 #define MAX_DATA_WRITE_UNLIMITED 256
 struct spi_programmer {
 	enum spi_controller type;
-	int max_data_read;
-	int max_data_write;
+	unsigned int max_data_read;
+	unsigned int max_data_write;
 	int (*command)(unsigned int writecnt, unsigned int readcnt,
 		   const unsigned char *writearr, unsigned char *readarr);
 	int (*multicommand)(struct spi_command *cmds);
 
 	/* Optimized functions for this programmer */
-	int (*read)(struct flashchip *flash, uint8_t *buf, int start, int len);
-	int (*write_256)(struct flashchip *flash, uint8_t *buf, int start, int len);
+	int (*read)(struct flashchip *flash, uint8_t *buf, unsigned int start, unsigned int len);
+	int (*write_256)(struct flashchip *flash, uint8_t *buf, unsigned int start, unsigned int len);
 };
 
 extern const struct spi_programmer *spi_programmer;
 int default_spi_send_command(unsigned int writecnt, unsigned int readcnt,
 			     const unsigned char *writearr, unsigned char *readarr);
 int default_spi_send_multicommand(struct spi_command *cmds);
-int default_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len);
-int default_spi_write_256(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 default_spi_write_256(struct flashchip *flash, uint8_t *buf, unsigned int start, unsigned int len);
 void register_spi_programmer(const struct spi_programmer *programmer);
 
 /* ichspi.c */
@@ -610,7 +610,7 @@
 void serprog_delay(int delay);
 int serprog_spi_send_command(unsigned int writecnt, unsigned int readcnt,
 			const unsigned char *writearr, unsigned char *readarr);
-int serprog_spi_read(struct flashchip *flash, uint8_t *buf, int start, int len);
+int serprog_spi_read(struct flashchip *flash, uint8_t *buf, unsigned int start, unsigned int len);
 #endif
 
 /* serial.c */