diff --git a/zerver/lib/test_classes.py b/zerver/lib/test_classes.py
index 580d8c9200..bf40b809af 100644
--- a/zerver/lib/test_classes.py
+++ b/zerver/lib/test_classes.py
@@ -499,12 +499,14 @@ class ZulipTestCase(TestCase):
         bulk_remove_subscriptions([user_profile], [stream])
 
     # Subscribe to a stream by making an API request
-    def common_subscribe_to_streams(self, email, streams, extra_post_data={}, invite_only=False):
-        # type: (Text, Iterable[Text], Dict[str, Any], bool) -> HttpResponse
+    def common_subscribe_to_streams(self, email, streams, extra_post_data={}, invite_only=False,
+                                    **kwargs):
+        # type: (Text, Iterable[Text], Dict[str, Any], bool, **Any) -> HttpResponse
         post_data = {'subscriptions': ujson.dumps([{"name": stream} for stream in streams]),
                      'invite_only': ujson.dumps(invite_only)}
         post_data.update(extra_post_data)
-        result = self.client_post("/api/v1/users/me/subscriptions", post_data, **self.api_auth(email))
+        result = self.client_post("/api/v1/users/me/subscriptions", post_data,
+                                  **self.api_auth(email), **kwargs)
         return result
 
     def send_json_payload(self, user_profile, url, payload, stream_name=None, **post_params):
diff --git a/zerver/tests/test_subs.py b/zerver/tests/test_subs.py
index 1b98f699bf..9a06c7a2d8 100644
--- a/zerver/tests/test_subs.py
+++ b/zerver/tests/test_subs.py
@@ -1458,6 +1458,7 @@ class SubscriptionAPITest(ZulipTestCase):
             extra_post_data=dict(
                 announce='true'
             ),
+            subdomain="testrealm",
         )
         self.assert_json_success(result)
 
@@ -1836,6 +1837,7 @@ class SubscriptionAPITest(ZulipTestCase):
                     self.mit_email("starnine"),
                     streams,
                     dict(principals=ujson.dumps([self.mit_email("starnine")])),
+                    subdomain="zephyr",
                 )
         # Make sure Zephyr mirroring realms such as MIT do not get
         # any tornado subscription events
@@ -2486,7 +2488,8 @@ class GetSubscribersTest(ZulipTestCase):
             email,
             ["mit_invite_only"],
             dict(principals=ujson.dumps(users_to_subscribe)),
-            invite_only=True)
+            invite_only=True,
+            subdomain="zephyr")
         self.assert_json_success(ret)
 
         with queries_captured() as queries:
@@ -2644,6 +2647,6 @@ class AccessStreamTest(ZulipTestCase):
             access_stream_by_name(sipbtest, mit_stream.name)
 
         # But they can access streams they are subscribed to
-        self.common_subscribe_to_streams(sipbtest.email, [mit_stream.name])
+        self.common_subscribe_to_streams(sipbtest.email, [mit_stream.name], subdomain="zephyr")
         access_stream_by_id(sipbtest, mit_stream.id)
         access_stream_by_name(sipbtest, mit_stream.name)