1 files changed, 5 insertions, 3 deletions
diff --git a/src/pip/_internal/metadata/base.py b/src/pip/_internal/metadata/base.py
index 100168b6e..37f9a8232 100644
--- a/src/pip/_internal/metadata/base.py
+++ b/src/pip/_internal/metadata/base.py
@@ -1,11 +1,13 @@
 import logging
 import re
-from typing import Container, Iterator, List, Optional
+from typing import Container, Iterator, List, Optional, Union
 
-from pip._vendor.packaging.version import _BaseVersion
+from pip._vendor.packaging.version import LegacyVersion, Version
 
 from pip._internal.utils.misc import stdlib_pkgs  # TODO: Move definition here.
 
+DistributionVersion = Union[LegacyVersion, Version]
+
 logger = logging.getLogger(__name__)
 
 
@@ -34,7 +36,7 @@ class BaseDistribution:
 
     @property
     def version(self):
-        # type: () -> _BaseVersion
+        # type: () -> DistributionVersion
         raise NotImplementedError()
 
     @property