diff --git a/ch341a_spi.c b/ch341a_spi.c
index d3af32f..17c37eb 100644
--- a/ch341a_spi.c
+++ b/ch341a_spi.c
@@ -335,7 +335,7 @@
 	stored_delay_us += usecs;
 }
 
-static int ch341a_spi_spi_send_command(struct flashctx *flash, unsigned int writecnt, unsigned int readcnt, const unsigned char *writearr, unsigned char *readarr)
+static int ch341a_spi_spi_send_command(const struct flashctx *flash, unsigned int writecnt, unsigned int readcnt, const unsigned char *writearr, unsigned char *readarr)
 {
 	if (handle == NULL)
 		return -1;