diff --git a/it85spi.c b/it85spi.c
index 5ce9193..b998790 100644
--- a/it85spi.c
+++ b/it85spi.c
@@ -270,7 +270,7 @@
 	return 0;
 }
 
-static int it85xx_spi_send_command(struct flashctx *flash,
+static int it85xx_spi_send_command(const struct flashctx *flash,
 				   unsigned int writecnt, unsigned int readcnt,
 				   const unsigned char *writearr,
 				   unsigned char *readarr);
@@ -322,7 +322,7 @@
  *   3. read date from LPC/FWH address 0xffff_fdxxh (drive CE# low and get
  *      data from MISO)
  */
-static int it85xx_spi_send_command(struct flashctx *flash,
+static int it85xx_spi_send_command(const struct flashctx *flash,
 				   unsigned int writecnt, unsigned int readcnt,
 				   const unsigned char *writearr,
 				   unsigned char *readarr)