diff --git a/importlib_metadata/__init__.py b/importlib_metadata/__init__.py
index edcf2691..2e5e953d 100644
--- a/importlib_metadata/__init__.py
+++ b/importlib_metadata/__init__.py
@@ -157,8 +157,9 @@ def __reduce__(self):
 
 class EntryPoints(tuple):
     """
-    A collection of EntryPoint objects, retrievable by name.
+    An immutable collection of EntryPoint objects, retrievable by name.
     """
+    __slots__ = ()
 
     def __getitem__(self, name) -> EntryPoint:
         try:
@@ -173,8 +174,9 @@ def names(self):
 
 class GroupedEntryPoints(tuple):
     """
-    A collection of EntryPoint objects, retrievable by group.
+    An immutable collection of EntryPoint objects, retrievable by group.
     """
+    __slots__ = ()
 
     def __getitem__(self, group) -> EntryPoints:
         return EntryPoints(ep for ep in self if ep.group == group)