diff --git a/samo-lib/drivers/src/mmc.c b/samo-lib/drivers/src/mmc.c
index 6385644cf..e40417d81 100644
--- a/samo-lib/drivers/src/mmc.c
+++ b/samo-lib/drivers/src/mmc.c
@@ -406,6 +406,8 @@ DSTATUS mmc_disk_initialize (
 		MODE_MASTER |
 		ENA |
 		0;
+	REG_SPI_CTL2 = 0;                               // must be zero for master mode
+	REG_SPI_WAIT = 0;
 
 	turn_on_power();					/* Force socket power on */
 	SELECT();