5 files changed, 19 insertions, 5 deletions
diff --git a/beautifulsoup/__init__.py b/beautifulsoup/__init__.py
index ca32589..968be08 100644
--- a/beautifulsoup/__init__.py
+++ b/beautifulsoup/__init__.py
@@ -121,10 +121,10 @@ class BeautifulSoup(Tag):
     @classmethod
     def default_builder(self):
         try:
-            from builder.html5_builder import HTML5TreeBuilder
+            from builder import HTML5TreeBuilder
             return HTML5TreeBuilder()
         except ImportError:
-            from builder.lxml_builder import LXMLTreeBuilder
+            from builder import LXMLTreeBuilder
             return LXMLTreeBuilder()
 
     def __init__(self, markup="", builder=None, parseOnlyThese=None,
@@ -258,12 +258,15 @@ class BeautifulSoup(Tag):
 
         tag = Tag(self, self.builder, name, attrs, self.currentTag,
                   self.previous)
+        if tag is None:
+            return tag
         if self.previous:
             self.previous.next = tag
         self.previous = tag
         self.pushTag(tag)
         return tag
 
+
     def handle_endtag(self, name):
         #print "End tag: " + name
         self.endData()
diff --git a/beautifulsoup/builder/__init__.py b/beautifulsoup/builder/__init__.py
index 9ffa9ef..d6c750c 100644
--- a/beautifulsoup/builder/__init__.py
+++ b/beautifulsoup/builder/__init__.py
@@ -7,7 +7,6 @@ __all__ = [
     'TreeBuilder',
     ]
 
-
 class TreeBuilder(Entities):
     """Turn a document into a Beautiful Soup object tree."""
 
@@ -163,3 +162,6 @@ class HTMLTreeBuilder(TreeBuilder):
                         raise StopParsing
                     pass
         return False
+
+from _lxml import *
+from _html5lib import *
diff --git a/beautifulsoup/builder/html5lib_builder.py b/beautifulsoup/builder/_html5lib.py
index 0a24ce1..9cca0b0 100644
--- a/beautifulsoup/builder/html5lib_builder.py
+++ b/beautifulsoup/builder/_html5lib.py
@@ -1,3 +1,7 @@
+__all__ = [
+    'HTML5TreeBuilder',
+    ]
+
 from beautifulsoup.builder import HTMLTreeBuilder, SAXTreeBuilder
 import html5lib
 from html5lib.constants import DataLossWarning
@@ -217,6 +221,6 @@ class TextNode(Element):
         html5lib.treebuilders._base.Node.__init__(self, None)
         self.element = element
         self.soup = soup
-    
+
     def cloneNode(self):
         raise NotImplementedError
diff --git a/beautifulsoup/builder/lxml_builder.py b/beautifulsoup/builder/_lxml.py
index 9f4c0bd..c2f368c 100644
--- a/beautifulsoup/builder/lxml_builder.py
+++ b/beautifulsoup/builder/_lxml.py
@@ -1,3 +1,8 @@
+__all__ = [
+    'LXMLTreeBuilderForXML',
+    'LXMLTreeBuilder',
+    ]
+
 from lxml import etree
 from beautifulsoup.element import Comment, Doctype
 from beautifulsoup.builder import TreeBuilder, HTMLTreeBuilder
diff --git a/beautifulsoup/testing.py b/beautifulsoup/testing.py
index 9b1e858..8fd9abf 100644
--- a/beautifulsoup/testing.py
+++ b/beautifulsoup/testing.py
@@ -3,7 +3,7 @@
 import unittest
 from beautifulsoup import BeautifulSoup
 from beautifulsoup.element import Comment, SoupStrainer
-from beautifulsoup.builder.lxml_builder import LXMLTreeBuilder
+from beautifulsoup.builder import LXMLTreeBuilder
 
 class SoupTest(unittest.TestCase):