--- doc/Makefile.in.orig	Tue May 13 02:47:22 2014
+++ doc/Makefile.in	Sat Jul 12 16:56:45 2014
@@ -299,7 +299,7 @@ build_vendor = @build_vendor@
 builddir = @builddir@
 datadir = @datadir@
 datarootdir = @datarootdir@
-docdir = @docdir@
+docdir = $(DESTDIR)$(DOCDIR)
 dvidir = @dvidir@
 exec_prefix = @exec_prefix@
 host = @host@