diff --git a/Lib/runpy.py b/Lib/runpy.py
index 6e94d6b..f251081 100644
--- a/Lib/runpy.py
+++ b/Lib/runpy.py
@@ -67,6 +67,7 @@
         run_globals.update(init_globals)
     run_globals.update(__name__ = mod_name,
                        __file__ = mod_fname,
+                       __cached__ = None,
                        __loader__ = mod_loader,
                        __package__ = pkg_name)
     exec(code, run_globals)
@@ -130,6 +131,7 @@
        At the very least, these variables in __main__ will be overwritten:
            __name__
            __file__
+           __cached__
            __loader__
            __package__
     """