diff --git a/bacnet-stack/ports/atmega168/Makefile b/bacnet-stack/ports/atmega168/Makefile
index 81189598..9ae00bc6 100644
--- a/bacnet-stack/ports/atmega168/Makefile
+++ b/bacnet-stack/ports/atmega168/Makefile
@@ -56,7 +56,6 @@ DEMOSRC = $(BACNET_DEMO)/handler/txbuf.c \
 # core BACnet stack files
 CORESRC =  \
 	$(BACNET_CORE)/crc.c \
-	$(BACNET_CORE)/apdu.c \
 	$(BACNET_CORE)/npdu.c \
 	$(BACNET_CORE)/bacdcode.c \
 	$(BACNET_CORE)/bacint.c \