diff --git a/src/if_python3.c b/src/if_python3.c
index f8dafd2..4067517 100644
--- a/src/if_python3.c
+++ b/src/if_python3.c
@@ -657,7 +657,7 @@
 static PyObject *globals;
 
 static int PythonIO_Init(void);
-PyMODINIT_FUNC Py3Init_vim(void);
+static PyObject *Py3Init_vim(void);
 
 /******************************************************
  * 1. Python interpreter main program.
@@ -1773,8 +1773,8 @@
 
 static struct PyModuleDef vimmodule;
 
-#ifndef PROTO
-PyMODINIT_FUNC Py3Init_vim(void)
+    static PyObject *
+Py3Init_vim(void)
 {
     PyObject *mod;
     PyObject *tmp;
@@ -1824,7 +1824,6 @@
 
     return mod;
 }
-#endif
 
 /*************************************************************************
  * 4. Utility functions for handling the interface between Vim and Python.