diff --git a/notebook/services/contents/manager.py b/notebook/services/contents/manager.py
index e8b34e684..af645a851 100644
--- a/notebook/services/contents/manager.py
+++ b/notebook/services/contents/manager.py
@@ -4,7 +4,6 @@
 # Distributed under the terms of the Modified BSD License.
 
 from fnmatch import fnmatch
-import gettext
 import itertools
 import json
 import os
@@ -32,6 +31,7 @@ from traitlets import (
 from ipython_genutils.py3compat import string_types
 from notebook.base.handlers import IPythonHandler
 
+
 copy_pat = re.compile(r'\-Copy\d*\.')
 
 
@@ -317,22 +317,31 @@ class ContentsManager(LoggingConfigurable):
             The name of a file, including extension
         path : unicode
             The API path of the target's directory
+        insert: unicode
+            The characters to insert after the base filename
 
         Returns
         -------
         name : unicode
             A filename that is unique, based on the input filename.
         """
-        path = path.strip('/')
-        basename, ext = os.path.splitext(filename)
+        # Extract the full suffix from the filename (e.g. .tar.gz)
+        dirname = os.path.dirname(filename)
+        basename = os.path.basename(filename)
+        parts = basename.split('.')
+        basename = os.path.join(dirname, parts[0])
+        suffix = '.' + '.'.join(parts[1:])
+        if suffix == '.':
+            suffix = ''
+
         for i in itertools.count():
             if i:
                 insert_i = '{}{}'.format(insert, i)
             else:
                 insert_i = ''
-            name = u'{basename}{insert}{ext}'.format(basename=basename,
-                insert=insert_i, ext=ext)
-            if not self.exists(u'{}/{}'.format(path, name)):
+            name = u'{basename}{insert}{suffix}'.format(basename=basename,
+                insert=insert_i, suffix=suffix)
+            if not self.exists(os.path.join(path, name)):
                 break
         return name
 
diff --git a/notebook/services/contents/tests/test_manager.py b/notebook/services/contents/tests/test_manager.py
index 0b4e5a4ea..0e6b0fb2b 100644
--- a/notebook/services/contents/tests/test_manager.py
+++ b/notebook/services/contents/tests/test_manager.py
@@ -300,6 +300,12 @@ class TestContentsManager(TestCase):
         self.assertEqual(model['name'], 'untitled')
         self.assertEqual(model['path'], '%s/untitled' % sub_dir)
 
+        # Test with a compound extension
+        model = cm.new_untitled(path=sub_dir, ext='.foo.bar')
+        self.assertEqual(model['name'], 'untitled.foo.bar')
+        model = cm.new_untitled(path=sub_dir, ext='.foo.bar')
+        self.assertEqual(model['name'], 'untitled1.foo.bar')
+
     def test_modified_date(self):
 
         cm = self.contents_manager