diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index c930893300..f72b80c704 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -1334,7 +1334,7 @@ static int sd_set_card_speed(struct mmc *mmc, enum bus_mode mode)
 	return 0;
 }
 
-int sd_select_bus_width(struct mmc *mmc, int w)
+static int sd_select_bus_width(struct mmc *mmc, int w)
 {
 	int err;
 	struct mmc_cmd cmd;