diff --git a/configs/io_defconfig b/configs/io_defconfig
index e6e205a..1c9323a 100644
--- a/configs/io_defconfig
+++ b/configs/io_defconfig
@@ -1,5 +1,6 @@
 CONFIG_PPC=y
 CONFIG_IDENT_STRING=" io 0.06"
+# CONFIG_MMC is not set
 CONFIG_4xx=y
 CONFIG_TARGET_IO=y
 CONFIG_FIT=y