--- AnyEvent/lib/AnyEvent/Handle.pm	2010/10/12 06:47:54	1.200
+++ AnyEvent/lib/AnyEvent/Handle.pm	2010/10/13 01:15:57	1.201
@@ -767,6 +767,9 @@
    *$timeout = sub {
       my ($self, $new_value) = @_;
 
+      $new_value >= 0
+         or Carp::croak "AnyEvent::Handle->$timeout called with negative timeout ($new_value), caught";
+
       $self->{$timeout} = $new_value;
       delete $self->{$tw}; &$cb;
    };