diff --git a/core/net/mac/Makefile.mac b/core/net/mac/Makefile.mac
index 600a228e8..799318e29 100644
--- a/core/net/mac/Makefile.mac
+++ b/core/net/mac/Makefile.mac
@@ -1 +1 @@
-CONTIKI_SOURCEFILES += xmac.c
+CONTIKI_SOURCEFILES += xmac.c nullmac.c