diff --git a/mongoengine/base/datastructures.py b/mongoengine/base/datastructures.py
index 3f7354a3..91403de9 100644
--- a/mongoengine/base/datastructures.py
+++ b/mongoengine/base/datastructures.py
@@ -1,5 +1,4 @@
 import weakref
-import functools
 import itertools
 from mongoengine.common import _import_class
 from mongoengine.errors import DoesNotExist, MultipleObjectsReturned
diff --git a/mongoengine/base/metaclasses.py b/mongoengine/base/metaclasses.py
index 7a104da9..8a25ff3d 100644
--- a/mongoengine/base/metaclasses.py
+++ b/mongoengine/base/metaclasses.py
@@ -1,13 +1,11 @@
 import warnings
 
-import pymongo
-
 from mongoengine.common import _import_class
 from mongoengine.errors import InvalidDocumentError
 from mongoengine.python_support import PY3
 from mongoengine.queryset import (DO_NOTHING, DoesNotExist,
                                   MultipleObjectsReturned,
-                                  QuerySet, QuerySetManager)
+                                  QuerySetManager)
 
 from mongoengine.base.common import _document_registry, ALLOW_INHERITANCE
 from mongoengine.base.fields import BaseField, ComplexBaseField, ObjectIdField
diff --git a/mongoengine/python_support.py b/mongoengine/python_support.py
index 2c4df00c..1214b490 100644
--- a/mongoengine/python_support.py
+++ b/mongoengine/python_support.py
@@ -12,7 +12,7 @@ if PY3:
         return codecs.latin_1_encode(s)[0]
 
     bin_type = bytes
-    txt_type   = str
+    txt_type = str
 else:
     try:
         from cStringIO import StringIO
diff --git a/mongoengine/queryset/transform.py b/mongoengine/queryset/transform.py
index 68adefbc..e8cd2721 100644
--- a/mongoengine/queryset/transform.py
+++ b/mongoengine/queryset/transform.py
@@ -6,7 +6,7 @@ from bson import SON
 from mongoengine.base.fields import UPDATE_OPERATORS
 from mongoengine.connection import get_connection
 from mongoengine.common import _import_class
-from mongoengine.errors import InvalidQueryError, LookUpError
+from mongoengine.errors import InvalidQueryError
 
 __all__ = ('query', 'update')
 
diff --git a/mongoengine/queryset/visitor.py b/mongoengine/queryset/visitor.py
index e5d2e615..84365f56 100644
--- a/mongoengine/queryset/visitor.py
+++ b/mongoengine/queryset/visitor.py
@@ -1,8 +1,5 @@
 import copy
 
-from itertools import product
-from functools import reduce
-
 from mongoengine.errors import InvalidQueryError
 from mongoengine.queryset import transform