diff -ruN old/Makefile new/Makefile
--- old/Makefile	2015-04-13 16:53:03.000000000 +0200
+++ new/Makefile	2015-07-31 15:52:08.920097812 +0200
@@ -346,7 +346,7 @@
 AWK		= awk
 PERL		= perl
 PYTHON		= python
-DTC		= dtc
+DTC		= $(DTCDIR)dtc
 CHECK		= sparse
 
 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
