diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 00ebf7af7467..3f559c0f1879 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -213,11 +213,11 @@ static struct attribute *mtd_attrs[] = {
 	NULL,
 };
 
-struct attribute_group mtd_group = {
+static struct attribute_group mtd_group = {
 	.attrs		= mtd_attrs,
 };
 
-struct attribute_group *mtd_groups[] = {
+static struct attribute_group *mtd_groups[] = {
 	&mtd_group,
 	NULL,
 };