diff --git a/telethon/client/auth.py b/telethon/client/auth.py
index d143dd0e..18670c79 100644
--- a/telethon/client/auth.py
+++ b/telethon/client/auth.py
@@ -137,7 +137,7 @@ class AuthMethods(MessageParseMethods, UserMethods):
     async def _start(
             self, phone, password, bot_token, force_sms,
             code_callback, first_name, last_name, max_attempts):
-        if not self.is_connected():
+        if not self.is_connected:
             await self.connect()
 
         if await self.is_user_authorized():
diff --git a/telethon/client/telegrambaseclient.py b/telethon/client/telegrambaseclient.py
index e200a0e9..8de83724 100644
--- a/telethon/client/telegrambaseclient.py
+++ b/telethon/client/telegrambaseclient.py
@@ -432,6 +432,7 @@ class TelegramBaseClient(abc.ABC):
 
         self._updates_handle = self._loop.create_task(self._update_loop())
 
+    @property
     def is_connected(self: 'TelegramClient') -> bool:
         """
         Returns ``True`` if the user has connected.
@@ -441,11 +442,11 @@ class TelegramBaseClient(abc.ABC):
         Example
             .. code-block:: python
 
-                while client.is_connected():
+                while client.is_connected:
                     await asyncio.sleep(1)
         """
         sender = getattr(self, '_sender', None)
-        return sender and sender.is_connected()
+        return sender and sender.is_connected
 
     def disconnect(self: 'TelegramClient'):
         """
diff --git a/telethon/client/updates.py b/telethon/client/updates.py
index bda6bac1..6a501e1d 100644
--- a/telethon/client/updates.py
+++ b/telethon/client/updates.py
@@ -323,7 +323,7 @@ class UpdateMethods(UserMethods):
     async def _update_loop(self: 'TelegramClient'):
         # Pings' ID don't really need to be secure, just "random"
         rnd = lambda: random.randrange(-2**63, 2**63)
-        while self.is_connected():
+        while self.is_connected:
             try:
                 await asyncio.wait_for(
                     self.disconnected, timeout=60, loop=self._loop
@@ -425,7 +425,7 @@ class UpdateMethods(UserMethods):
                 )
                 break
             except Exception as e:
-                if not isinstance(e, asyncio.CancelledError) or self.is_connected():
+                if not isinstance(e, asyncio.CancelledError) or self.is_connected:
                     name = getattr(callback, '__name__', repr(callback))
                     self._log[__name__].exception('Unhandled exception on %s',
                                                   name)
diff --git a/telethon_examples/gui.py b/telethon_examples/gui.py
index 949d1eb9..140cd248 100644
--- a/telethon_examples/gui.py
+++ b/telethon_examples/gui.py
@@ -228,7 +228,7 @@ class App(tkinter.Tk):
         """
         Sends a message. Does nothing if the client is not connected.
         """
-        if not self.cl.is_connected():
+        if not self.cl.is_connected:
             return
 
         # The user needs to configure a chat where the message should be sent.