diff --git a/docker/types/services.py b/docker/types/services.py
index 69c0c498ea..63456bf8fe 100644
--- a/docker/types/services.py
+++ b/docker/types/services.py
@@ -244,7 +244,7 @@ class Mount(dict):
           for the ``volume`` type.
         subpath (str): Path inside a volume to mount instead of the volume root.
         tmpfs_size (int or string): The size for the tmpfs mount in bytes.
-        tmpfs_mode (int): The permission mode for the tmpfs mount.
+        tmpfs_mode (int): The permission mode in octal for the tmpfs mount (e.g. ``0o777``).
     """
 
     def __init__(self, target, source, type='volume', read_only=False,