diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
index 1de855d29ad4c4f138099487aca96feddb981fa2..a4f7e8e689d3a16190ed67114ce7da06b49766f7 100644
--- a/drivers/mmc/host/mmci_stm32_sdmmc.c
+++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
@@ -25,8 +25,8 @@ struct sdmmc_priv {
 	void *sg_cpu;
 };
 
-int sdmmc_idma_validate_data(struct mmci_host *host,
-			     struct mmc_data *data)
+static int sdmmc_idma_validate_data(struct mmci_host *host,
+				    struct mmc_data *data)
 {
 	struct scatterlist *sg;
 	int i;