diff --git a/Doc/c-api/module.rst b/Doc/c-api/module.rst
--- a/Doc/c-api/module.rst
+++ b/Doc/c-api/module.rst
@@ -54,20 +54,23 @@ Module Objects
    string instead of a Unicode object.
 
 
 .. c:function:: PyObject* PyModule_GetDict(PyObject *module)
 
    .. index:: single: __dict__ (module attribute)
 
    Return the dictionary object that implements *module*'s namespace; this object
-   is the same as the :attr:`~object.__dict__` attribute of the module object.  This
-   function never fails.  It is recommended extensions use other
-   :c:func:`PyModule_\*` and :c:func:`PyObject_\*` functions rather than directly
-   manipulate a module's :attr:`~object.__dict__`.
+   is the same as the :attr:`~object.__dict__` attribute of the module object.
+   If *module* is not a module object (or a subtype of a module object),
+   :exc:`SystemError` is raised and *NULL* is returned.
+
+   It is recommended extensions use other :c:func:`PyModule_\*` and
+   :c:func:`PyObject_\*` functions rather than directly manipulate a module's
+   :attr:`~object.__dict__`.
 
 
 .. c:function:: PyObject* PyModule_GetNameObject(PyObject *module)
 
    .. index::
       single: __name__ (module attribute)
       single: SystemError (built-in exception)
 
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -439,18 +439,17 @@ PyObject *
 PyModule_GetDict(PyObject *m)
 {
     PyObject *d;
     if (!PyModule_Check(m)) {
         PyErr_BadInternalCall();
         return NULL;
     }
     d = ((PyModuleObject *)m) -> md_dict;
-    if (d == NULL)
-        ((PyModuleObject *)m) -> md_dict = d = PyDict_New();
+    assert(d != NULL);
     return d;
 }
 
 PyObject*
 PyModule_GetNameObject(PyObject *m)
 {
     _Py_IDENTIFIER(__name__);
     PyObject *d;