Follow-up of PEP 3121:

Correct the exported symbol for extension modules built by distutils

Lib/distutils/command/build_ext.py

@@ -646,10 +646,10 @@ class build_ext(Command):
     def get_export_symbols(self, ext):
         """Return the list of symbols that a shared extension has to
         export.  This either uses 'ext.export_symbols' or, if it's not
-        provided, "init" + module_name.  Only relevant on Windows, where
+        provided, "PyInit_" + module_name.  Only relevant on Windows, where
         the .pyd file (DLL) must export the module "init" function.
         """
-        initfunc_name = "init" + ext.name.split('.')[-1]
+        initfunc_name = "PyInit_" + ext.name.split('.')[-1]
         if initfunc_name not in ext.export_symbols:
             ext.export_symbols.append(initfunc_name)
         return ext.export_symbols