diff --git a/lib/importlib_metadata/__init__.py b/lib/importlib_metadata/__init__.py
index 26a1388c..9a36a8e6 100644
--- a/lib/importlib_metadata/__init__.py
+++ b/lib/importlib_metadata/__init__.py
@@ -346,7 +346,7 @@ class FileHash:
         return f'<FileHash mode: {self.mode} value: {self.value}>'
 
 
-class Distribution:
+class Distribution(metaclass=abc.ABCMeta):
     """A Python distribution package."""
 
     @abc.abstractmethod