diff --git a/firmware/ice40-riscv/icE1usb/Makefile b/firmware/ice40-riscv/icE1usb/Makefile
index b2f85d1..06f5484 100644
--- a/firmware/ice40-riscv/icE1usb/Makefile
+++ b/firmware/ice40-riscv/icE1usb/Makefile
@@ -49,6 +49,7 @@
 	e1.h \
 	misc.h \
 	usb_desc_ids.h \
+	usb_e1.h \
 	usb_str_app.gen.h \
 	$(NULL)