Index: trunk/pois/configure.ac
===================================================================
--- trunk/pois/configure.ac	(revision 3821)
+++ trunk/pois/configure.ac	(revision 3829)
@@ -21,7 +21,17 @@
 AC_SUBST([pois_CFLAGS])
 
-AC_PROG_SWIG(1.3.24)
+AC_PROG_SWIG(1.3.21)
 SWIG_MULTI_MODULE_SUPPORT
 SWIG_PYTHON
+
+dnl lifted from autoconf 2.59's configure.ac
+AC_PATH_PROG([PERL], perl, no)
+AC_SUBST([PERL])dnl
+if test "$PERL" = no; then
+  AC_MSG_ERROR([perl is not found])
+fi
+$PERL -e 'require 5.005_03;' || {
+   AC_MSG_ERROR([Perl 5.005_03 or better is required])
+}
 
 AC_CONFIG_FILES([