diff --git a/django/test/client.py b/django/test/client.py
index 4d57f2d2ab..ea2fd32d3f 100644
--- a/django/test/client.py
+++ b/django/test/client.py
@@ -191,7 +191,7 @@ class Client:
             'REQUEST_METHOD':    'GET',
             'SCRIPT_NAME':       '',
             'SERVER_NAME':       'testserver',
-            'SERVER_PORT':       80,
+            'SERVER_PORT':       '80',
             'SERVER_PROTOCOL':   'HTTP/1.1',
         }
         environ.update(self.defaults)