Index: test/tc_mech.rb
===================================================================
--- test/tc_mech.rb	(revision 475)
+++ test/tc_mech.rb	(working copy)
@@ -25,6 +25,12 @@
     @agent.get('http://localhost/', [], 'http://tenderlovemaking.com/')
     assert_equal 'http://tenderlovemaking.com/', @agent.request['Referer']
   end
+  
+  def test_get_with_file_referer
+    assert_nothing_raised do
+      @agent.get('http://localhost', [], WWW::Mechanize::File.new(URI.parse('http://tenderlovemaking.com/crossdomain.xml')))
+    end
+  end
 
   def test_weird_url
     assert_nothing_raised {
Index: lib/www/mechanize.rb
===================================================================
--- lib/www/mechanize.rb	(revision 475)
+++ lib/www/mechanize.rb	(working copy)
@@ -168,7 +168,7 @@
       # FIXME: Huge hack so that using a URI as a referer works.  I need to
       # refactor everything to pass around URIs but still support
       # WWW::Mechanize::Page#base
-      unless referer.is_a?(Page)
+      unless referer.is_a?(WWW::Mechanize::File)
         referer = referer.is_a?(String) ?
           Page.new(URI.parse(referer), {'content-type' => 'text/html'}) :
           Page.new(referer, {'content-type' => 'text/html'})