diff --git a/oauth2/__init__.py b/oauth2/__init__.py
index a1776a75..b4c0e23a 100644
--- a/oauth2/__init__.py
+++ b/oauth2/__init__.py
@@ -651,6 +651,9 @@ def request(self, uri, method="GET", body=b'', headers=None,
         redirections=httplib2.DEFAULT_MAX_REDIRECTS, connection_type=None):
         DEFAULT_POST_CONTENT_TYPE = 'application/x-www-form-urlencoded'
 
+        if body is None:
+            body = b''
+
         if not isinstance(headers, dict):
             headers = {}