diff --git a/django/contrib/gis/tests/geogapp/models.py b/django/contrib/gis/tests/geogapp/models.py
index ce637c38a5..f6f127ca96 100644
--- a/django/contrib/gis/tests/geogapp/models.py
+++ b/django/contrib/gis/tests/geogapp/models.py
@@ -21,6 +21,7 @@ class City(NamedModel):
 
 
 class Zipcode(NamedModel):
+    code = models.CharField(max_length=10)
     poly = models.PolygonField(geography=True)