diff --git a/bitbang_spi.c b/bitbang_spi.c
index 7c183c3..ac50e67 100644
--- a/bitbang_spi.c
+++ b/bitbang_spi.c
@@ -64,7 +64,7 @@
 	return master->get_miso();
 }
 
-static int bitbang_spi_send_command(struct flashctx *flash,
+static int bitbang_spi_send_command(const struct flashctx *flash,
 				    unsigned int writecnt, unsigned int readcnt,
 				    const unsigned char *writearr,
 				    unsigned char *readarr);
@@ -145,7 +145,7 @@
 	}
 }
 
-static int bitbang_spi_send_command(struct flashctx *flash,
+static int bitbang_spi_send_command(const struct flashctx *flash,
 				    unsigned int writecnt, unsigned int readcnt,
 				    const unsigned char *writearr,
 				    unsigned char *readarr)