diff --git a/Makefile.PL b/Makefile.PL
index 0d38d27..bf9b8d7 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -3,8 +3,8 @@ use ExtUtils::MakeMaker;
 WriteMakefile(
     'NAME'         => 'Martnet::DDNS',
     'VERSION_FROM' => 'DDNS.pm',
-    'PREREQ_PM'    => { Net::DNS => 0.8,
-			File::Temp => 0.2304,
+    'PREREQ_PM'    => { Net::DNS => 0.66,
+			File::Temp => 0.22,
 			Regexp::Common => 2013031301,
     },
     'EXE_FILES'    => [ 'bin/add-vhost',
diff --git a/bin/sync-slave b/bin/sync-slave
index bf2f6c6..bb27d11 100755
--- a/bin/sync-slave
+++ b/bin/sync-slave
@@ -5,6 +5,8 @@ use warnings;
 use Martnet::DDNS;
 use File::Temp qw/tempfile/;
 
+my $force = shift; # a "force" flag, if the update is big
+
 my $ddns = Martnet::DDNS->new();
 
 my @vh = $ddns->get();
@@ -15,12 +17,17 @@ my @all = parse_slavefile("/etc/bind/martnet.slave.zones.9");
 my $changecount = 0;
 foreach my $i (@vh) {
     unless (contains_zone($i, @all)) {
-	# If we find any differences, we rewrite the file
-	do_rewrite(@vh);
-	last;
+	$changecount++;
     }
 }
 
+die "Cowardly refusing to make a big update automatically"
+    if ($changecount > 10 && !$force);
+
+if ($changecount) {
+    do_rewrite(@vh);
+}
+
 exit 0;
 
 sub parse_slavefile {