--- Makefile.orig	2011-06-21 13:24:59.000000000 +0200
+++ Makefile	2011-06-21 13:34:51.000000000 +0200
@@ -3,7 +3,7 @@
 # Should make just about anywhere...  If you have problems,
 # check out porting.c first
 
-CC            = gcc
+CC            ?= gcc
 
 # at present, no include directories needed
 # Except on our OSF3.0, where -I/usr/include is needed (why? I dont know).
@@ -19,7 +19,7 @@
 #         Do not use it if it takes none (SunOS, HPUX, OSF1 )
 #         It works either way, just gets rid of a warning.
 
-CFLAGS	              =  -I/usr/include $(DEBUGFLAG) $(INCLUDEDIR)
+CFLAGS	              +=  -I/usr/include $(DEBUGFLAG) $(INCLUDEDIR)
 
 # for SunOS cc, just use the above
 # for cc on HPUX: