--- Makefile.in.orig	2020-10-17 15:00:00 UTC
+++ Makefile.in
@@ -4,6 +4,7 @@ prefix := @PREFIX@
 bindir := @BINDIR@
 datarootdir := @DATAROOTDIR@
 datadir := @DATADIR@/@PACKAGE_NAME@
+docdir := @DOCDIR@
 package_name := @PACKAGE_NAME@
 package_version := @PACKAGE_VERSION@
 package_full := $(package_name)-$(package_version)
@@ -194,7 +195,7 @@ install:
 	 $(DESTDIR)$(datarootdir)/applications \
 	 $(DESTDIR)$(datarootdir)/icons/hicolor/48x48/apps \
 	 $(DESTDIR)$(datarootdir)/icons/hicolor/scalable/apps \
-	 $(DESTDIR)$(datadir)/doc \
+	 $(DESTDIR)$(docdir) \
 	 $(DESTDIR)$(datadir)/13x13 \
 	 $(DESTDIR)$(datadir)/16x16 \
 	 $(DESTDIR)$(datadir)/20x20 \
@@ -207,7 +208,7 @@ install:
 	$(instfile) desktop/icons/hicolor/48x48/apps/azpainterb.png $(DESTDIR)$(datarootdir)/icons/hicolor/48x48/apps
 	$(instfile) desktop/icons/hicolor/scalable/apps/azpainterb.svg $(DESTDIR)$(datarootdir)/icons/hicolor/scalable/apps
 
-	$(instfile) GPL3 AUTHORS ChangeLog README README_ja manual_ja.html $(DESTDIR)$(datadir)/doc
+	$(instfile) AUTHORS ChangeLog README README_ja manual_ja.html $(DESTDIR)$(docdir)
 
 	$(instfile) data/brushlist.dat data/grad.dat data/sckey.conf \
 	 data/coltype.png data/icon.png data/texlib.dat \