diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8b94869..1de5a4c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,11 @@
 Changelog
 =========
 
+8.1.1
+-----
+
+- Fix marking messages as read via Microsoft Graph
+
 8.1.0
 -----
 
diff --git a/parsedmarc/__init__.py b/parsedmarc/__init__.py
index 5e4cbfa..5002676 100644
--- a/parsedmarc/__init__.py
+++ b/parsedmarc/__init__.py
@@ -34,7 +34,7 @@ from parsedmarc.utils import is_outlook_msg, convert_outlook_msg
 from parsedmarc.utils import parse_email
 from parsedmarc.utils import timestamp_to_human, human_timestamp_to_datetime
 
-__version__ = "8.1.0"
+__version__ = "8.1.1"
 
 formatter = logging.Formatter(
     fmt='%(levelname)8s:%(filename)s:%(lineno)d:%(message)s',
diff --git a/parsedmarc/mail/graph.py b/parsedmarc/mail/graph.py
index 8be8e9a..4373c7f 100644
--- a/parsedmarc/mail/graph.py
+++ b/parsedmarc/mail/graph.py
@@ -66,7 +66,7 @@ class MSGraphConnection(MailboxConnection):
     def mark_message_read(self, message_id: str):
         """Marks a message as read"""
         url = f'/users/{self.mailbox_name}/messages/{message_id}'
-        resp = self._client.patch(url, data={"isRead": "true"})
+        resp = self._client.patch(url, json={"isRead": "true"})
         if resp.status_code != 200:
             raise RuntimeWarning(f"Failed to mark message read"
                                  f"{resp.status_code}: {resp.json()}")
diff --git a/setup.py b/setup.py
index f5cabb1..6bbf6d2 100644
--- a/setup.py
+++ b/setup.py
@@ -14,7 +14,7 @@ from setuptools import setup
 from codecs import open
 from os import path
 
-__version__ = "8.1.0"
+__version__ = "8.1.1"
 
 description = "A Python package and CLI for parsing aggregate and " \
               "forensic DMARC reports"