diff --git a/oauth2client/tools.py b/oauth2client/tools.py
index 235793b..20faa43 100644
--- a/oauth2client/tools.py
+++ b/oauth2client/tools.py
@@ -99,9 +99,9 @@ class ClientRedirectHandler(BaseHTTPServer.BaseHTTPRequestHandler):
query = self.path.split('?', 1)[-1]
query = dict(urllib.parse.parse_qsl(query))
self.server.query_params = query
- self.wfile.write("Authentication Status")
- self.wfile.write("The authentication flow has completed.
")
- self.wfile.write("")
+ self.wfile.write(b"Authentication Status")
+ self.wfile.write(b"The authentication flow has completed.
")
+ self.wfile.write(b"")
def log_message(self, format, *args):
"""Do not log messages to stdout while running as command line program."""