diff --git a/firmware/usb-dfu-project/Makefile b/firmware/usb-dfu-project/Makefile
index 9fe75e4..d41be19 100644
--- a/firmware/usb-dfu-project/Makefile
+++ b/firmware/usb-dfu-project/Makefile
@@ -138,6 +138,8 @@ VPATH += $(USB)/common/audio
 
 # Objects built from C source files
 C_OBJECTS += main.o
+C_OBJECTS += hardware.o
+C_OBJECTS += slimpro.o
 C_OBJECTS += dfu_desc.o
 C_OBJECTS += sam3u_chipid_usbserial.o
 C_OBJECTS += USBD_UDPHS.o