--- Makefile.orig	2008-09-12 13:58:19.000000000 +0200
+++ Makefile	2009-02-24 14:36:26.000000000 +0100
@@ -28,10 +28,10 @@
   $(error Please define PREFIX)
 endif
 
-bindir          := ${PREFIX}/bin
-docdir		:= ${PREFIX}/share/doc/menhir
-libdir	        := ${PREFIX}/share/menhir
-mandir          := ${PREFIX}/share/man/man1
+bindir          ?= ${PREFIX}/bin
+docdir		?= ${PREFIX}/share/doc/menhir
+libdir	        ?= ${PREFIX}/share/menhir
+mandir          ?= ${PREFIX}/share/man/man1
 MANS            := menhir.1
 DOCS            := manual.pdf demos
 MLYLIB          := src/standard.mly
@@ -64,11 +64,9 @@
 install: src/menhir
 	mkdir -p $(bindir)
 	mkdir -p $(libdir)
-	mkdir -p $(docdir)
 	mkdir -p $(mandir)
 	install src/menhir $(bindir)
 	install -m 644 $(MLYLIB) $(libdir)
-	cp -r $(DOCS) $(docdir)
 	cp -r $(MANS) $(mandir)
 	@cd src && if $(USE_OCAMLFIND) ; then \
 	  echo Installing MenhirLib via ocamlfind. ; \
@@ -78,6 +76,10 @@
 	  install -m 644 $(MENHIRLIB) $(libdir) ; \
 	fi
 
+docinstall:
+	mkdir -p $(docdir)
+	cp -r $(DOCS) $(docdir)
+
 uninstall:
 	rm -rf $(bindir)/menhir
 	rm -rf $(libdir)