diff --git a/pickit2_spi.c b/pickit2_spi.c
index 2936ee8..0bc17af 100644
--- a/pickit2_spi.c
+++ b/pickit2_spi.c
@@ -195,7 +195,7 @@
 	return 0;
 }
 
-static int pickit2_spi_send_command(struct flashctx *flash, unsigned int writecnt, unsigned int readcnt,
+static int pickit2_spi_send_command(const struct flashctx *flash, unsigned int writecnt, unsigned int readcnt,
 				     const unsigned char *writearr, unsigned char *readarr)
 {