diff -r 72f974a255dc ChangeLog
--- a/ChangeLog	Fri Oct 05 02:54:33 2007 +0000
+++ b/ChangeLog	Fri Oct 05 20:08:28 2007 -0400
@@ -1,3 +1,7 @@ 2007-10-04  Joel E. Denny  <address@hidden
+2007-10-05  Claudio Saavedra  <address@hidden>
+
+	* configure.ac: Print an error message if texinfo or flex are missing.
+
 2007-10-04  Joel E. Denny  <address@hidden>
 
 	Implement --print-datadir.
diff -r 72f974a255dc configure.ac
--- a/configure.ac	Fri Oct 05 02:54:33 2007 +0000
+++ b/configure.ac	Fri Oct 05 20:08:28 2007 -0400
@@ -80,6 +80,9 @@ AC_SUBST([YACC_LIBRARY])
 
 # Checks for programs.
 AC_PROG_LEX
+if test "$LEX" != flex; then
+   AC_MSG_ERROR([GNU Flex is required])
+fi
 AC_PROG_YACC
 AC_PROG_RANLIB
 BISON_PROG_GNU_M4
@@ -87,6 +90,10 @@ if test x"$ac_cv_prog_gnu_m4" != xyes; t
   AC_MSG_ERROR([GNU M4 1.4 is required])
 fi
 AC_DEFINE_UNQUOTED([M4], ["$M4"], [Define to the GNU M4 executable name.])
+AC_CHECK_PROG([makeinfo],makeinfo,yes)
+if test x"$makeinfo" != xyes; then 
+  AC_MSG_ERROR([texinfo is required])
+fi
 
 # Checks for header files.
 AC_CHECK_HEADERS_ONCE([locale.h])