Strange prototype problem

Sorry for the slightly off-topic post.

I have a piece of Javascript that I am using to make an Ajax call
using prototype. It works fine in Firefox and IE 7, but is giving a
syntax error in Safari 2.04. Can anyone see what is wrong with this
code?

function makeRequest() {
  url = /ajaxtest/index
  new Ajax.Request(url, {
    method: 'get',
    onSuccess: function success(t) { <------------- Safari gives a
syntax error on this line (Syntax error - parse error)
        alert('success');
      },
  onFailure: function failure(t) {
  alert('failed ajax');
      }
    } );
}

As far as I can tell this example is identical to the example in the
prototype.js api docs - I just cannot figure out what is wrong!

Thanks,

Stephen.