diff -N -a -u1 a/Makefile b/Makefile
--- a/Makefile	2016-01-03 14:41:40.000000000 +0100
+++ b/Makefile	2018-12-11 23:47:44.942218496 +0100
@@ -36,3 +36,3 @@
 	cp -f ./define.release ./define.h
-	make -C /lib/modules/$(shell uname -r)/build/ SUBDIRS=$(PWD) modules
+	+make -C $(KERNELDIR) SUBDIRS=$(PWD) modules
 debug: