diff --git a/IPython/utils/traitlets.py b/IPython/utils/traitlets.py
index 6c85e04..4557dda 100644
--- a/IPython/utils/traitlets.py
+++ b/IPython/utils/traitlets.py
@@ -1208,6 +1208,11 @@ 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