diff --git a/zerver/tests/test_subs.py b/zerver/tests/test_subs.py
index 925a3bcf66..2138a23afd 100644
--- a/zerver/tests/test_subs.py
+++ b/zerver/tests/test_subs.py
@@ -1770,23 +1770,17 @@ class DefaultStreamTest(ZulipTestCase):
         self.assert_json_success(result)
         self.assertFalse(stream_name in self.get_default_stream_names(user_profile.realm))
 
-        # Test admin can't add unsubscribed private stream
+        # Test admin can't access unsubscribed private stream for adding.
         stream_name = "private_stream"
         stream = self.make_stream(stream_name, invite_only=True)
         self.subscribe(self.example_user('iago'), stream_name)
         result = self.client_post('/json/default_streams', dict(stream_id=stream.id))
         self.assert_json_error(result, "Invalid stream id")
 
+        # Test admin can't add subscribed private stream also.
         self.subscribe(user_profile, stream_name)
         result = self.client_post('/json/default_streams', dict(stream_id=stream.id))
-        self.assert_json_success(result)
-        self.assertTrue(stream_name in self.get_default_stream_names(user_profile.realm))
-
-        # Test admin can remove unsubscribed private stream
-        self.unsubscribe(user_profile, stream_name)
-        result = self.client_delete('/json/default_streams', dict(stream_id=stream.id))
-        self.assert_json_success(result)
-        self.assertFalse(stream_name in self.get_default_stream_names(user_profile.realm))
+        self.assert_json_error(result, "Private streams cannot be made default.")
 
     def test_guest_user_access_to_streams(self) -> None:
         user_profile = self.example_user("polonius")
diff --git a/zerver/views/streams.py b/zerver/views/streams.py
index 0a22fbb5de..0dff51cb49 100644
--- a/zerver/views/streams.py
+++ b/zerver/views/streams.py
@@ -153,6 +153,8 @@ def add_default_stream(request: HttpRequest,
                        user_profile: UserProfile,
                        stream_id: int=REQ(validator=check_int)) -> HttpResponse:
     (stream, sub) = access_stream_by_id(user_profile, stream_id)
+    if stream.invite_only:
+        return json_error(_("Private streams cannot be made default."))
     do_add_default_stream(stream)
     return json_success()