diff --git a/common.mk b/common.mk
index c170f0b..0c24c7e 100644
--- a/common.mk
+++ b/common.mk
@@ -204,8 +204,9 @@
 	@touch ../out-br/extra.conf
 	@echo "BR2_TARGET_GENERIC_GETTY_PORT=\"$(BUILDROOT_GETTY_PORT)\"" >> \
 		../out-br/extra.conf
-	@echo "BR2_ROOTFS_OVERLAY=\"$(ROOT)/build/br-ext/board/qemu/overlay\"" >> \
-		../out-br/extra.conf
+ifneq (,$(BR2_ROOTFS_OVERLAY))
+	@echo "BR2_ROOTFS_OVERLAY=\"$(BR2_ROOTFS_OVERLAY)\"" >> ../out-br/extra.conf
+endif
 	@echo "BR2_PACKAGE_OPTEE_TEST_CROSS_COMPILE=\"$(CROSS_COMPILE_S_USER)\"" >> \
 		../out-br/extra.conf
 	@echo "BR2_PACKAGE_OPTEE_EXAMPLES_CROSS_COMPILE=\"$(CROSS_COMPILE_S_USER)\"" >> \
diff --git a/qemu.mk b/qemu.mk
index ea3e084..7933501 100644
--- a/qemu.mk
+++ b/qemu.mk
@@ -8,6 +8,8 @@
 override COMPILE_S_USER    := 32
 override COMPILE_S_KERNEL  := 32
 
+BR2_ROOTFS_OVERLAY = $(ROOT)/build/br-ext/board/qemu/overlay
+
 include common.mk
 
 ################################################################################
diff --git a/qemu_v8.mk b/qemu_v8.mk
index a705cfc..50af414 100644
--- a/qemu_v8.mk
+++ b/qemu_v8.mk
@@ -8,6 +8,8 @@
 override COMPILE_S_USER    := 64
 override COMPILE_S_KERNEL  := 64
 
+BR2_ROOTFS_OVERLAY = $(ROOT)/build/br-ext/board/qemu/overlay
+
 include common.mk
 
 ################################################################################