--- a/Build.PL	Tue Dec 29 21:40:48 2015 +0100
+++ b/Build.PL	Tue Dec 29 22:59:42 2015 +0100
@@ -5,4 +5,18 @@
     dist_version_from => 'lib/Once.pm',
     dist_abstract => 'once downloader',
     script_files => [qw(bin/once)],
+    share_dir => [qw(templates)],
+    requires => {
+	'perl' => '5.0.18',
+        'File::MimeInfo' => 0,
+	'Template' => 0,
+	'experimental' => 0,
+    },
 )->create_build_script;
+
+# create the var.tt to be included
+mkdir 'templates.var' or -d 'templates.var' or die "templates.var: $!";
+chomp(my $version = `hg log -r . --template '{latesttag}-{latesttagdistance}-{node|short}\n'`);
+open(my $o, '>', $_ = 'templates.var/version.tt') or die "Can't open $_: $!\n";
+print $o qq{[% vcs.version = "$version"; %]\n};
+