diff --git a/distutils/command/install.py b/distutils/command/install.py
index 40be5ba6..4f944725 100644
--- a/distutils/command/install.py
+++ b/distutils/command/install.py
@@ -395,6 +395,7 @@ def finalize_options(self):
                             'platlibdir': getattr(sys, 'platlibdir', 'lib'),
                             'implementation_lower': _get_implementation().lower(),
                             'implementation': _get_implementation(),
+                            'platsubdir': sysconfig.get_config_var('platsubdir'),
                            }
 
         if HAS_USER_SITE: