--- a/genshi/output.py
+++ b/genshi/output.py
@@ -176,17 +176,21 @@
                                  stripped from the output
         :note: Changed in 0.4.2: The  `doctype` parameter can now be a string.
         """
+        self.preamble = []
+        if doctype:
+            if isinstance(doctype, basestring):
+                doctype = DocType.get(doctype)
+            self.preamble.append((DOCTYPE, doctype, (None, -1, -1)))
         self.filters = [EmptyTagFilter()]
         if strip_whitespace:
             self.filters.append(WhitespaceFilter(self._PRESERVE_SPACE))
         self.filters.append(NamespaceFlattener(prefixes=namespace_prefixes))
-        if doctype:
-            self.filters.append(DocTypeInserter(doctype))
 
     def __call__(self, stream):
         have_decl = have_doctype = False
         in_cdata = False
 
+        stream = chain(self.preamble, stream)
         for filter_ in self.filters:
             stream = filter_(stream)
         for kind, data, pos in stream:
@@ -692,36 +696,3 @@
 
                 if kind:
                     yield kind, data, pos
-
-
-class DocTypeInserter(object):
-    """A filter that inserts the DOCTYPE declaration in the correct location,
-    after the XML declaration.
-    """
-    def __init__(self, doctype):
-        """Initialize the filter.
-
-        :param doctype: DOCTYPE as a string or DocType object.
-        """
-        if isinstance(doctype, basestring):
-            doctype = DocType.get(doctype)
-        self.doctype_event = (DOCTYPE, doctype, (None, -1, -1))
-
-    def __call__(self, stream):
-        buffer = []
-        doctype_inserted = False
-        for kind, data, pos in stream:
-            # Buffer whitespace TEXT and XML_DECL
-            if not doctype_inserted:
-                if kind is XML_DECL or (kind is TEXT and not data.strip()):
-                    buffer.append((kind, data, pos))
-                    continue
-
-                for event in buffer:
-                    yield event
-
-                yield self.doctype_event
-
-                doctype_inserted = True
-
-            yield (kind, data, pos)