--- makefile~	2009-11-15 12:11:22.000000000 +0100
+++ makefile	2009-12-05 19:53:57.000000000 +0100
@@ -5,8 +5,8 @@
 # This makefile does create and install all documentation.
 
 VERSION		= `cat VERSION`
-CFLAGS		+= -Wall -Wshadow -Wno-char-subscripts -fomit-frame-pointer # gcc specific flags
-CFLAGS		+= -O -DUNIX -DVERSION=\"$(VERSION)\"
+OPTFLAGS	+= -O -Wall -Wshadow -Wno-char-subscripts -fomit-frame-pointer # gcc specific flags
+CFLAGS		+= $(OPTFLAGS) -DUNIX -DVERSION=\"$(VERSION)\"
 LDLIBS		+= -lm # libraries to link
 
 # "make READLINE=1" to include readline support: