diff --git a/mongoengine/base.py b/mongoengine/base.py
index 0cf57ec5..a42ec449 100644
--- a/mongoengine/base.py
+++ b/mongoengine/base.py
@@ -654,7 +654,7 @@ class BaseDocument(object):
             for key, value in values.items():
                 setattr(self, key, value)
 
-        # Set any get_fieldname_display methodsF
+        # Set any get_fieldname_display methods
         self.__set_field_display()
         # Flag initialised
         self._initialised = True
@@ -841,7 +841,7 @@ class BaseDocument(object):
         if hasattr(self, '_changed_fields') and key not in self._changed_fields:
             self._changed_fields.append(key)
 
-    def _get_changed_fields(self, key='', inspected=[]):
+    def _get_changed_fields(self, key='', inspected=None):
         """Returns a list of all fields that have explicitly been changed.
         """
         from mongoengine import EmbeddedDocument, DynamicEmbeddedDocument