diff --git a/examples/wch/ch32v307-make-baremetal-builtin/Makefile b/examples/wch/ch32v307-make-baremetal-builtin/Makefile
index a3443e21..0c0a0989 100644
--- a/examples/wch/ch32v307-make-baremetal-builtin/Makefile
+++ b/examples/wch/ch32v307-make-baremetal-builtin/Makefile
@@ -34,7 +34,7 @@ flash: firmware.bin
 	wchisp flash $<
 #	@echo; echo "IMPORTANT: configure device to 96k RAM / 224k Flash"
 
-zip:
+zip: firmware.bin
 	zip -r ch32v307.modbus.firmware.`+%Y-%m-%d`.zip  firmware.*
 
 clean: