--- Makefile.orig	2016-08-21 06:54:46.000000000 +0200
+++ Makefile	2016-10-19 23:07:16.658682733 +0200
@@ -71,9 +71,9 @@
 # Make Configuration
 #
 CC ?= gcc
-COMPILER_OPTIONS = -Wall -O -g
+CFLAGS ?= -Wall -O -g
 
-CFLAGS= $(COMPILER_OPTIONS) -I. -DVERSION=\"$(VERSION)\" $(OMIT_GETOPT_LONG) $(FILEOFFSET_64BIT)
+CFLAGS += -I. -DVERSION=\"$(VERSION)\" $(OMIT_GETOPT_LONG) $(FILEOFFSET_64BIT)
 
 INSTALL_PROGRAM = $(INSTALL) -c -m 0755
 INSTALL_DATA    = $(INSTALL) -c -m 0644
