diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index e94e92001e7c..cf6a100bb38f 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -812,7 +812,7 @@ static void atmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 		slot->sdc_reg |= MCI_SDCBUS_1BIT;
 		break;
 	case MMC_BUS_WIDTH_4:
-		slot->sdc_reg = MCI_SDCBUS_4BIT;
+		slot->sdc_reg |= MCI_SDCBUS_4BIT;
 		break;
 	}