diff --git a/ChangeLog b/ChangeLog
index bfb902cc3..67ea1765d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -14,6 +14,10 @@
 	* src/gzip/zutil.h [MSDOS && !(__TURBOC__ || __BORLANDC__)]: Don't
 	include malloc.h.
 
+
+	* builds/unix/unix-def.in (datarootdir): Define, for autoconf 2.59c
+	and forthcoming versions.
+
 2006-04-28  Werner Lemberg  <wl@gnu.org>
 
 	* src/lzw/ftlzw.c, src/lzw/zopen.c, src/lzw/zopen.h: Removed,
diff --git a/builds/unix/unix-def.in b/builds/unix/unix-def.in
index 9a23b1cd0..1241db665 100644
--- a/builds/unix/unix-def.in
+++ b/builds/unix/unix-def.in
@@ -51,6 +51,7 @@ exec_prefix  := @exec_prefix@
 libdir       := @libdir@
 bindir       := @bindir@
 includedir   := @includedir@
+datarootdir  := @datarootdir@
 datadir      := @datadir@
 
 version_info := @version_info@