diff --git a/configs/mx31pdk_defconfig b/configs/mx31pdk_defconfig
index a31ad5b..bb1f121 100644
--- a/configs/mx31pdk_defconfig
+++ b/configs/mx31pdk_defconfig
@@ -3,6 +3,7 @@
 CONFIG_SPL_LIBGENERIC_SUPPORT=y
 CONFIG_SPL_NAND_SUPPORT=y
 CONFIG_SPL_SERIAL_SUPPORT=y
+# CONFIG_MMC is not set
 CONFIG_BOOTDELAY=1
 CONFIG_SPL=y
 CONFIG_CMD_BOOTZ=y