diff --git a/fbchat/_client.py b/fbchat/_client.py
index 3b9db45..c3a67a7 100644
--- a/fbchat/_client.py
+++ b/fbchat/_client.py
@@ -558,7 +558,7 @@ class Client:
             "shouldSendReadReceipt": "true",
         }
 
-        for threads in threads:
+        for thread in threads:
             data["ids[{}]".format(thread.id)] = "true" if read else "false"
 
         j = self.session._payload_post("/ajax/mercury/change_read_status.php", data)
diff --git a/tests/online/conftest.py b/tests/online/conftest.py
index ddf1663..33cea7b 100644
--- a/tests/online/conftest.py
+++ b/tests/online/conftest.py
@@ -17,12 +17,33 @@ def session(pytestconfig):
 
     pytestconfig.cache.set("session_cookies", session.get_cookies())
 
+    # TODO: Allow the main session object to be closed - and perhaps used in `with`?
+    session._session.close()
+
 
 @pytest.fixture
 def client(session):
     return fbchat.Client(session=session)
 
 
+@pytest.fixture(scope="session")
+def user(pytestconfig, session):
+    user_id = pytestconfig.cache.get("user_id", None)
+    if not user_id:
+        user_id = input("A user you're chatting with's id: ")
+        pytestconfig.cache.set("user_id", user_id)
+    return fbchat.User(session=session, id=user_id)
+
+
+@pytest.fixture(scope="session")
+def group(pytestconfig, session):
+    group_id = pytestconfig.cache.get("group_id", None)
+    if not group_id:
+        group_id = input("A group you're chatting with's id: ")
+        pytestconfig.cache.set("group_id", group_id)
+    return fbchat.Group(session=session, id=group_id)
+
+
 @pytest.fixture
 def listener(session):
     return fbchat.Listener(session=session, chat_on=False, foreground=False)
diff --git a/tests/online/test_client.py b/tests/online/test_client.py
index 3a17d8b..76d874d 100644
--- a/tests/online/test_client.py
+++ b/tests/online/test_client.py
@@ -1,5 +1,6 @@
 import pytest
 import fbchat
+import datetime
 import os
 
 pytestmark = pytest.mark.online
@@ -93,5 +94,9 @@ def test_upload_many(client, open_resource):
         )
 
 
-# def test_mark_as_read(client):
-#     client.mark_as_read([thread1, thread2])
+def test_mark_as_read(client, user, group):
+    client.mark_as_read([user, group], datetime.datetime.now())
+
+
+def test_mark_as_unread(client, user, group):
+    client.mark_as_unread([user, group], datetime.datetime.now())