diff --git a/google/cloud/firestore_v1/async_document.py b/google/cloud/firestore_v1/async_document.py
index 00672153c..dfcc5037b 100644
--- a/google/cloud/firestore_v1/async_document.py
+++ b/google/cloud/firestore_v1/async_document.py
@@ -14,8 +14,6 @@
 
 """Classes for representing documents for the Google Cloud Firestore API."""
 
-import six
-
 from google.cloud.firestore_v1.base_document import (
     BaseDocumentReference,
     DocumentSnapshot,
@@ -310,7 +308,7 @@ async def get(self, field_paths=None, transaction=None):
                 :attr:`create_time` attributes will all be ``None`` and
                 its :attr:`exists` attribute will be ``False``.
         """
-        if isinstance(field_paths, six.string_types):
+        if isinstance(field_paths, str):
             raise ValueError("'field_paths' must be a sequence of paths, not a string.")
 
         if field_paths is not None:
diff --git a/google/cloud/firestore_v1/async_transaction.py b/google/cloud/firestore_v1/async_transaction.py
index 569025465..f572c173f 100644
--- a/google/cloud/firestore_v1/async_transaction.py
+++ b/google/cloud/firestore_v1/async_transaction.py
@@ -18,8 +18,6 @@
 import asyncio
 import random
 
-import six
-
 from google.cloud.firestore_v1.base_transaction import (
     _BaseTransactional,
     BaseTransaction,
@@ -272,7 +270,7 @@ async def __call__(self, transaction, *args, **kwargs):
         """
         self._reset()
 
-        for attempt in six.moves.xrange(transaction._max_attempts):
+        for attempt in range(transaction._max_attempts):
             result = await self._pre_commit(transaction, *args, **kwargs)
             succeeded = await self._maybe_commit(transaction)
             if succeeded: