diff --git a/IPython/nbconvert/tests/test_nbconvertapp.py b/IPython/nbconvert/tests/test_nbconvertapp.py
index 855cb4f..bee17cf 100644
--- a/IPython/nbconvert/tests/test_nbconvertapp.py
+++ b/IPython/nbconvert/tests/test_nbconvertapp.py
@@ -46,7 +46,7 @@ class TestNbConvertApp(TestsBase):
         Do search patterns work for notebook names?
         """
         with self.create_temp_cwd(['notebook*.ipynb']):
-            self.call('nbconvert --to="python" --notebooks=*.ipynb')
+            self.call('nbconvert --to="python" --notebooks=\'["*.ipynb"]\'')
             assert os.path.isfile('notebook1.py')
             assert os.path.isfile('notebook2.py')
 
@@ -57,8 +57,8 @@ class TestNbConvertApp(TestsBase):
         """
         with self.create_temp_cwd():
             self.copy_files_to(['notebook*.ipynb'], 'subdir/')
-            self.call('nbconvert --to="python"'
-                      ' --notebooks=%s' % os.path.join('subdir', '*.ipynb'))
+            self.call('nbconvert --to="python" --notebooks='
+                      '\'["%s"]\'' % os.path.join('subdir', '*.ipynb'))
             assert os.path.isfile('notebook1.py')
             assert os.path.isfile('notebook2.py')
 
@@ -68,7 +68,8 @@ class TestNbConvertApp(TestsBase):
         Do explicit notebook names work?
         """
         with self.create_temp_cwd(['notebook*.ipynb']):
-            self.call('nbconvert --to="python" --notebooks=notebook2.ipynb')
+            self.call('nbconvert --to="python" --notebooks='
+                      '\'["notebook2.ipynb"]\'')
             assert not os.path.isfile('notebook1.py')
             assert os.path.isfile('notebook2.py')
 
@@ -93,8 +94,8 @@ class TestNbConvertApp(TestsBase):
         Do export templates work?
         """
         with self.create_temp_cwd(['notebook2.ipynb']):
-            self.call('nbconvert --to=slides --notebooks=notebook2.ipynb'
-                      ' --template=reveal')
+            self.call('nbconvert --to=slides --notebooks='
+                      '\'["notebook2.ipynb"]\' --template=reveal')
             assert os.path.isfile('notebook2.slides.html')
             with open('notebook2.slides.html') as f:
                 assert '/reveal.css' in f.read()
@@ -106,7 +107,7 @@ class TestNbConvertApp(TestsBase):
         """
         with self.create_temp_cwd(['notebook*.ipynb']):
             self.call('nbconvert --to="python" --notebooks='
-                      '*.ipynb,notebook1.ipynb,notebook2.ipynb')
+                      '\'["*.ipynb","notebook1.ipynb","notebook2.ipynb"]\'')
             assert os.path.isfile('notebook1.py')
             assert os.path.isfile('notebook2.py')
 
@@ -117,7 +118,7 @@ class TestNbConvertApp(TestsBase):
         """
         with self.create_temp_cwd(['notebook*.ipynb']):
             self.call('nbconvert --to="python" --notebooks='
-                      'notebook1.ipynb,notebook2.ipynb,*.ipynb')
+                      '\'["notebook1.ipynb","notebook2.ipynb","*.ipynb"]\'')
             assert os.path.isfile('notebook1.py')
             assert os.path.isfile('notebook2.py')
 
diff --git a/IPython/utils/traitlets.py b/IPython/utils/traitlets.py
index 4557dda..6c85e04 100644
--- a/IPython/utils/traitlets.py
+++ b/IPython/utils/traitlets.py
@@ -1208,11 +1208,6 @@ class Container(Instance):
         raise TraitError(e)
 
     def validate(self, obj, value):
-        # Command line arguments come in as strings, let's make them into
-        # lists so we can proceed with validation
-        if isinstance(value, basestring):
-            value = value.split(',')
-
         value = super(Container, self).validate(obj, value)
         if value is None:
             return value