diff --git a/IPython/html/base/handlers.py b/IPython/html/base/handlers.py
index 6c3dcdde0..eb2a7a71c 100644
--- a/IPython/html/base/handlers.py
+++ b/IPython/html/base/handlers.py
@@ -496,7 +496,6 @@ class FilesRedirectHandler(IPythonHandler):
 
 # path matches any number of `/foo[/bar...]` or just `/` or ''
 path_regex = r"(?P<path>(?:(?:/[^/]+)+|/?))"
-notebook_path_regex = r"(?P<path>(?:/[^/]+)+\.ipynb)"
 
 #-----------------------------------------------------------------------------
 # URL to handler mappings
diff --git a/IPython/html/nbconvert/handlers.py b/IPython/html/nbconvert/handlers.py
index 63ba2668e..40cca7f70 100644
--- a/IPython/html/nbconvert/handlers.py
+++ b/IPython/html/nbconvert/handlers.py
@@ -11,7 +11,7 @@ from tornado import web
 
 from ..base.handlers import (
     IPythonHandler, FilesRedirectHandler,
-    notebook_path_regex, path_regex,
+    path_regex,
 )
 from IPython.nbformat import from_dict
 
@@ -83,6 +83,8 @@ class NbconvertFileHandler(IPythonHandler):
         path = path.strip('/')
         model = self.contents_manager.get(path=path)
         name = model['name']
+        if model['type'] != 'notebook':
+            raise web.HTTPError(400, "Not a notebook: %s" % path)
 
         self.set_header('Last-Modified', model['last_modified'])
         
@@ -142,8 +144,8 @@ _format_regex = r"(?P<format>\w+)"
 
 
 default_handlers = [
-    (r"/nbconvert/%s%s" % (_format_regex, notebook_path_regex),
-         NbconvertFileHandler),
     (r"/nbconvert/%s" % _format_regex, NbconvertPostHandler),
+    (r"/nbconvert/%s%s" % (_format_regex, path_regex),
+         NbconvertFileHandler),
     (r"/nbconvert/html%s" % path_regex, FilesRedirectHandler),
 ]
diff --git a/IPython/html/notebook/handlers.py b/IPython/html/notebook/handlers.py
index f6e101209..65c171e0c 100644
--- a/IPython/html/notebook/handlers.py
+++ b/IPython/html/notebook/handlers.py
@@ -8,8 +8,7 @@ from tornado import web
 HTTPError = web.HTTPError
 
 from ..base.handlers import (
-    IPythonHandler, FilesRedirectHandler,
-    notebook_path_regex, path_regex,
+    IPythonHandler, FilesRedirectHandler, path_regex,
 )
 from ..utils import url_escape
 
@@ -23,9 +22,11 @@ class NotebookHandler(IPythonHandler):
         path = path.strip('/')
         cm = self.contents_manager
         
-        # a .ipynb filename was given
-        if not cm.file_exists(path):
-            raise web.HTTPError(404, u'Notebook does not exist: %s' % path)
+        # will raise 404 on not found
+        model = cm.get(path, content=False)
+        if model['type'] != 'notebook':
+            # not a notebook, redirect to files
+            return FilesRedirectHandler.get(self, path)
         name = url_escape(path.rsplit('/', 1)[-1])
         path = url_escape(path)
         self.write(self.render_template('notebook.html',
@@ -43,7 +44,6 @@ class NotebookHandler(IPythonHandler):
 
 
 default_handlers = [
-    (r"/notebooks%s" % notebook_path_regex, NotebookHandler),
-    (r"/notebooks%s" % path_regex, FilesRedirectHandler),
+    (r"/notebooks%s" % path_regex, NotebookHandler),
 ]
 
diff --git a/IPython/html/tests/test_paths.py b/IPython/html/tests/test_paths.py
index 18dc4ad7a..01b24fe02 100644
--- a/IPython/html/tests/test_paths.py
+++ b/IPython/html/tests/test_paths.py
@@ -2,7 +2,7 @@
 import re
 import nose.tools as nt
 
-from IPython.html.base.handlers import path_regex, notebook_path_regex
+from IPython.html.base.handlers import path_regex
 
 try: # py3
     assert_regex = nt.assert_regex
@@ -14,7 +14,6 @@ except AttributeError: # py2
 
 # build regexps that tornado uses:
 path_pat = re.compile('^' + '/x%s' % path_regex + '$')
-nb_path_pat = re.compile('^' + '/y%s' % notebook_path_regex + '$')
 
 def test_path_regex():
     for path in (
@@ -39,23 +38,3 @@ def test_path_regex_bad():
         '/y/x/foo',
     ):
         assert_not_regex(path, path_pat)
-
-def test_notebook_path_regex():
-    for path in (
-        '/y/asdf.ipynb',
-        '/y/foo/bar.ipynb',
-        '/y/a/b/c/d/e.ipynb',
-    ):
-        assert_regex(path, nb_path_pat)
-
-def test_notebook_path_regex_bad():
-    for path in (
-        '/y',
-        '/y/',
-        '/y/.ipynb',
-        '/y/foo/.ipynb',
-        '/y/foo/bar',
-        '/yfoo.ipynb',
-        '/yfoo/bar.ipynb',
-    ):
-        assert_not_regex(path, nb_path_pat)