diff --git a/rcon/readline.py b/rcon/readline.py
index 9de0f6b..a7da816 100644
--- a/rcon/readline.py
+++ b/rcon/readline.py
@@ -19,6 +19,8 @@ HIST_FILE = Path.home().joinpath('.rconshell_history')
 class CommandHistory:
     """Context manager for the command line history."""
 
+    __slots__ = ('logger',)
+
     def __init__(self, logger: Logger):
         """Sets the logger to use."""
         self.logger = logger