Index: lib/hpricot/builder.rb
===================================================================
--- lib/hpricot/builder.rb	(revision 159)
+++ lib/hpricot/builder.rb	(working copy)
@@ -7,7 +7,8 @@
     34 => '"', # quotation mark
     38 => '&',  # ampersand
     60 => '<',   # left angle bracket
-    62 => '>'    # right angle bracket
+    62 => '>',   # right angle bracket
+    39 => '''  # apostrophe
   }
   PREDEFINED_U = PREDEFINED.inject({}) { |hsh, (k, v)| hsh[v] = k; hsh }