Index: doc/Makefile.in
--- doc/Makefile.in.orig
+++ doc/Makefile.in
@@ -278,7 +278,7 @@ PYTHON_PLATFORM = @PYTHON_PLATFORM@
 PYTHON_PREFIX = @PYTHON_PREFIX@
 PYTHON_VERSION = @PYTHON_VERSION@
 RANLIB = @RANLIB@
-RRDDOCDIR = @RRDDOCDIR@
+RRDDOCDIR = $(datadir)/doc/rrdtool
 RRDGRAPH_YLEGEND_ANGLE = @RRDGRAPH_YLEGEND_ANGLE@
 RRD_DEFAULT_FONT = @RRD_DEFAULT_FONT@
 RUBY = @RUBY@