fix python 3 mod init function declaration (closes #26827)
diff --git a/Doc/howto/cporting.rst b/Doc/howto/cporting.rst
index d7a7086..27e7e6f 100644
--- a/Doc/howto/cporting.rst
+++ b/Doc/howto/cporting.rst
@@ -161,7 +161,7 @@
 
    #define INITERROR return NULL
 
-   PyObject *
+   PyMODINIT_FUNC
    PyInit_myextension(void)
 
    #else