diff --git a/src/controller/mastodon/messages.py b/src/controller/mastodon/messages.py
index b23691af..4620132f 100644
--- a/src/controller/mastodon/messages.py
+++ b/src/controller/mastodon/messages.py
@@ -9,8 +9,9 @@ from sessions.mastodon import templates
 from wxUI.dialogs.mastodon import tootDialogs
 
 class toot(messages.basicTweet):
-    def __init__(self, session, title, caption, text="", max=500, *args, **kwargs):
-        self.max = max
+    def __init__(self, session, title, caption, text="", *args, **kwargs):
+        # take max character limit from session as this might be different for some instances.
+        self.max = session.char_limit
         self.title = title
         self.session = session
         self.message = tootDialogs.Toot(caption=caption, text=text, *args, **kwargs)
diff --git a/src/sessions/mastodon/session.py b/src/sessions/mastodon/session.py
index 308def98..499688cf 100644
--- a/src/sessions/mastodon/session.py
+++ b/src/sessions/mastodon/session.py
@@ -28,6 +28,7 @@ class Session(base.baseSession):
         self.supported_languages = []
         self.type = "mastodon"
         self.db["pagination_info"] = dict()
+        self.char_limit = 500
 
     def login(self, verify_credentials=True):
         if self.settings["mastodon"]["access_token"] != None and self.settings["mastodon"]["instance"] != None:
@@ -73,6 +74,10 @@ class Session(base.baseSession):
             self.supported_languages = self.api.instance().languages
         self.get_lists()
         self.get_muted_users()
+        # determine instance custom characters limit.
+        instance = self.api.instance()
+        if hasattr(instance, "max_toot_chars"):
+            self.char_limit = instance.max_toot_chars
         self.settings.write()
 
     def get_lists(self):