diff --git a/include/image-commands.mk b/include/image-commands.mk
index 15084093d2..ff8acf96c4 100644
--- a/include/image-commands.mk
+++ b/include/image-commands.mk
@@ -316,6 +316,15 @@ define Build/gzip
 	@mv $@.new $@
 endef
 
+define Build/gzip-filename
+	@mkdir -p $@.tmp
+	@cp $@ $@.tmp/$(word 1,$(1))
+	$(if $(SOURCE_DATE_EPOCH),touch -hcd "@$(SOURCE_DATE_EPOCH)" $@.tmp/$(word 1,$(1)) $(word 2,$(1)))
+	$(STAGING_DIR_HOST)/bin/gzip -f -9 -N -c $@.tmp/$(word 1,$(1)) $(word 2,$(1)) > $@.new
+	@mv $@.new $@
+	@rm -rf $@.tmp
+endef
+
 define Build/install-dtb
 	$(call locked, \
 		$(foreach dts,$(DEVICE_DTS), \
diff --git a/include/image.mk b/include/image.mk
index 5d9d4acb41..01bc3bda86 100644
--- a/include/image.mk
+++ b/include/image.mk
@@ -359,6 +359,7 @@ define Device/Init
   ARTIFACTS :=
   DEVICE_IMG_PREFIX := $(IMG_PREFIX)-$(1)
   DEVICE_IMG_NAME = $$(DEVICE_IMG_PREFIX)-$$(1)-$$(2)
+  FACTORY_IMG_NAME :=
   IMAGE_SIZE :=
   KERNEL_PREFIX = $$(DEVICE_IMG_PREFIX)
   KERNEL_SUFFIX := -kernel.bin
@@ -418,6 +419,7 @@ DEFAULT_DEVICE_VARS := \
   DEVICE_FDT_NUM DEVICE_IMG_PREFIX SOC BOARD_NAME UIMAGE_MAGIC UIMAGE_NAME \
   SUPPORTED_DEVICES IMAGE_METADATA KERNEL_ENTRY KERNEL_LOADADDR \
   UBOOT_PATH IMAGE_SIZE \
+  FACTORY_IMG_NAME \
   DEVICE_PACKAGES DEVICE_COMPAT_VERSION DEVICE_COMPAT_MESSAGE \
   DEVICE_VENDOR DEVICE_MODEL DEVICE_VARIANT \
   DEVICE_ALT0_VENDOR DEVICE_ALT0_MODEL DEVICE_ALT0_VARIANT \