--- doc/Makefile.in.orig	2019-02-02 19:08:09.000000000 +0900
+++ doc/Makefile.in	2019-03-15 23:14:07.557427000 +0900
@@ -16,7 +16,7 @@
 @SET_MAKE@
 
 VPATH = @srcdir@
-pkgdatadir = $(datadir)/@PACKAGE@
+pkgdatadir = $(docdir)
 pkgincludedir = $(includedir)/@PACKAGE@
 pkglibdir = $(libdir)/@PACKAGE@
 pkglibexecdir = $(libexecdir)/@PACKAGE@