diff --git a/chatmastermind/chat.py b/chatmastermind/chat.py
index 84fd9b5..1a12d64 100644
--- a/chatmastermind/chat.py
+++ b/chatmastermind/chat.py
@@ -52,12 +52,12 @@ def read_dir(dir_path: Path,
     Parameters:
     * 'dir_path': source directory
     * 'glob': if specified, files will be filtered using 'path.glob()',
-      otherwise it uses 'path.iterdir()'.
+      otherwise it uses '*{msg_suffix}'.
     * 'mfilter': use with 'Message.from_file()' to filter messages
       when reading them.
     """
     messages: list[Message] = []
-    file_iter = dir_path.glob(glob) if glob else dir_path.iterdir()
+    file_iter = dir_path.glob(glob) if glob else dir_path.glob(f'*{msg_suffix}')
     for file_path in sorted(file_iter):
         if (file_path.is_file()
            and file_path.name not in ignored_files  # noqa: W503