diff --git a/extensions/ipset/GNUmakefile.in b/extensions/ipset/GNUmakefile.in
index d473a3a..a5d8a39 100644
--- a/extensions/ipset/GNUmakefile.in
+++ b/extensions/ipset/GNUmakefile.in
@@ -2,6 +2,7 @@
 
 top_srcdir      := @top_srcdir@
 srcdir          := @srcdir@
+datarootdir     := @datarootdir@
 abstop_srcdir   := $(shell readlink -e ${top_srcdir})
 abssrcdir       := $(shell readlink -e ${srcdir})