diff --git a/docs/index.html b/docs/index.html
index ca0ea7e..215b5d2 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -19,7 +19,7 @@ Python PDF parser and analyzer
 
 <div align=right class=lastmod>
 <!-- hhmts start -->
-Last Modified: Mon Mar 22 06:16:28 UTC 2010
+Last Modified: Tue Mar 23 10:29:24 UTC 2010
 <!-- hhmts end -->
 </div>
 
@@ -335,17 +335,18 @@ no stream header is displayed for the ease of saving it to a file.
 <ul>
 <li> <A href="http://www.python.org/dev/peps/pep-0008/">PEP-8</a> and
 <a href="http://www.python.org/dev/peps/pep-0257/">PEP-257</a> conformance.
+<li> Better documentation.
 <li> Better text extraction / layout analysis.
-<li> Better API Documentation.
+<li> Robust error handling.
 <li> Crypt stream filter support. (More sample documents are needed!)
 <li> CCITTFax stream filter support.
-<li> Robust error handling.
 </ul>
 
 <a name="changes"></a>
 <hr noshade>
 <h2>Changes</h2>
 <ul>
+<li> 2010/03/xx: Bugfixes. Thanks to Brian Berry and Lubos Pintes.
 <li> 2010/03/22: Improved layout analysis. Added regression tests.
 <li> 2010/03/12: A couple of bugfixes. Thanks to Sean Manefield.
 <li> 2010/02/27: Changed the way of internal layout handling. (LTTextItem -&gt; LTChar)
diff --git a/pdfminer/pdfparser.py b/pdfminer/pdfparser.py
index 2581888..44e515c 100644
--- a/pdfminer/pdfparser.py
+++ b/pdfminer/pdfparser.py
@@ -361,7 +361,7 @@ class PDFDocument(object):
             self._initialized = True
             return
         (docid, param) = self.encryption
-        if literal_name(param['Filter']) != 'Standard':
+        if literal_name(param.get('Filter')) != 'Standard':
             raise PDFEncryptionError('Unknown filter: param=%r' % param)
         V = int_value(param.get('V', 0))
         if not (V == 1 or V == 2):
@@ -439,6 +439,7 @@ class PDFDocument(object):
             else:
                 if STRICT:
                     raise PDFSyntaxError('Cannot locate objid=%r' % objid)
+                # return null for a nonexistent reference.
                 return None
             if strmid:
                 stream = stream_value(self.getobj(strmid))
@@ -588,6 +589,7 @@ class PDFParser(PSStackParser):
         return
 
     KEYWORD_R = KWD('R')
+    KEYWORD_NULL = KWD('null')
     KEYWORD_ENDOBJ = KWD('endobj')
     KEYWORD_STREAM = KWD('stream')
     KEYWORD_XREF = KWD('xref')
@@ -596,10 +598,16 @@ class PDFParser(PSStackParser):
         if token in (self.KEYWORD_XREF, self.KEYWORD_STARTXREF):
             self.add_results(*self.pop(1))
             return
+        
         if token is self.KEYWORD_ENDOBJ:
             self.add_results(*self.pop(4))
             return
 
+        if token is self.KEYWORD_NULL:
+            # null object
+            self.push((pos, None))
+            return
+
         if token is self.KEYWORD_R:
             # reference to indirect object
             try:
diff --git a/pdfminer/psparser.py b/pdfminer/psparser.py
index 64cb169..676793f 100644
--- a/pdfminer/psparser.py
+++ b/pdfminer/psparser.py
@@ -537,7 +537,8 @@ class PSStackParser(PSBaseParser):
                     (pos, objs) = self.end_type('d')
                     if len(objs) % 2 != 0:
                         raise PSSyntaxError('Invalid dictionary construct: %r' % objs)
-                    d = dict( (literal_name(k), v) for (k,v) in choplist(2, objs))
+                    # construct a Python dictionary.
+                    d = dict( (literal_name(k), v) for (k,v) in choplist(2, objs) if v is not None )
                     self.push((pos, d))
                 except PSTypeError:
                     if STRICT: raise