diff --git a/target/linux/ramips/image/mt7620.mk b/target/linux/ramips/image/mt7620.mk
index d435e9f587..84999f08de 100644
--- a/target/linux/ramips/image/mt7620.mk
+++ b/target/linux/ramips/image/mt7620.mk
@@ -145,8 +145,8 @@ define Device/ex3700
   DTS := EX3700
   BLOCKSIZE := 4k
   IMAGE_SIZE := 7744k
-  IMAGES += factory.bin
-  IMAGE/factory.bin := $$(sysupgrade_bin) | check-size $$$$(IMAGE_SIZE) | netgear-chk
+  IMAGES += factory.chk
+  IMAGE/factory.chk := $$(sysupgrade_bin) | check-size $$$$(IMAGE_SIZE) | netgear-chk
   DEVICE_PACKAGES := -kmod-mt76 kmod-mt76x2
   DEVICE_TITLE := Netgear EX3700
 endef