diff --git a/arch/arm/src/kinetis/kinetis_sdhc.c b/arch/arm/src/kinetis/kinetis_sdhc.c
index 9fafc7b3b82..077c42676ed 100644
--- a/arch/arm/src/kinetis/kinetis_sdhc.c
+++ b/arch/arm/src/kinetis/kinetis_sdhc.c
@@ -310,7 +310,7 @@ static void  kinetis_blocksetup(FAR struct sdio_dev_s *dev,
 static int  kinetis_recvsetup(FAR struct sdio_dev_s *dev,
               FAR uint8_t *buffer, size_t nbytes);
 static int  kinetis_sendsetup(FAR struct sdio_dev_s *dev,
-              FAR const uint8_t *buffer, uint32_t nbytes);
+              FAR const uint8_t *buffer, size_t nbytes);
 #endif
 
 static int  kinetis_cancel(FAR struct sdio_dev_s *dev);