diff --git a/sys/dev/mmc/mmc.c b/sys/dev/mmc/mmc.c
index d89af3bc784f..c3f96c9adb3a 100644
--- a/sys/dev/mmc/mmc.c
+++ b/sys/dev/mmc/mmc.c
@@ -239,8 +239,8 @@ mmc_rescan_cards(struct mmc_softc *sc)
 static uint32_t
 mmc_select_vdd(struct mmc_softc *sc, uint32_t ocr)
 {
-    // XXX
-	return ocr;
+
+	return ocr & MMC_OCR_VOLTAGE;
 }
 
 static int
diff --git a/sys/dev/mmc/mmcreg.h b/sys/dev/mmc/mmcreg.h
index 1b868cbaffb8..fddaf9763583 100644
--- a/sys/dev/mmc/mmcreg.h
+++ b/sys/dev/mmc/mmcreg.h
@@ -292,6 +292,7 @@ struct mmc_request {
  *
  * The MMC_OCR_CCS appears to be valid for only SD cards.
  */
+#define MMC_OCR_VOLTAGE	0x3fffffffU	/* Vdd Voltage mask */
 #define	MMC_OCR_LOW_VOLTAGE (1u << 7)	/* Low Voltage Range -- tbd */
 #define	MMC_OCR_200_210	(1U << 8)	/* Vdd voltage 2.00 ~ 2.10 */
 #define	MMC_OCR_210_220	(1U << 9)	/* Vdd voltage 2.10 ~ 2.20 */