-DOCPREFIX:=$(shell echo "@prefix@" | grep rrd >/dev/null && echo "rrdtool-@VERSION@/")
-idocdir = $(prefix)/shared/doc/$(DOCPREFIX)txt
+DOCPREFIX:=$(shell echo "@prefix@" | grep rrd >/dev/null || echo "rrdtool-@VERSION@/")
+idocdir = $(prefix)/share/doc/$(DOCPREFIX)txt