diff --git a/digilent_spi.c b/digilent_spi.c
index 13a876e..0f7a9da 100644
--- a/digilent_spi.c
+++ b/digilent_spi.c
@@ -257,7 +257,7 @@
 	return 0;
 }
 
-static int digilent_spi_send_command(struct flashctx *flash, unsigned int writecnt, unsigned int readcnt,
+static int digilent_spi_send_command(const struct flashctx *flash, unsigned int writecnt, unsigned int readcnt,
 				     const unsigned char *writearr, unsigned char *readarr)
 {
 	int ret;