diff --git a/mstarddc_spi.c b/mstarddc_spi.c
index db11157..48d6204 100644
--- a/mstarddc_spi.c
+++ b/mstarddc_spi.c
@@ -153,7 +153,7 @@
 }
 
 /* Returns 0 upon success, a negative number upon errors. */
-static int mstarddc_spi_send_command(struct flashctx *flash,
+static int mstarddc_spi_send_command(const struct flashctx *flash,
 				     unsigned int writecnt,
 				     unsigned int readcnt,
 				     const unsigned char *writearr,