diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 872956500c27..66037511f2d7 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -2521,6 +2521,10 @@ static int __init of_unittest(void)
 	int res;
 
 	/* adding data for unittest */
+
+	if (IS_ENABLED(CONFIG_UML))
+		unittest_unflatten_overlay_base();
+
 	res = unittest_data_add();
 	if (res)
 		return res;