diff --git a/Include/pystate.h b/Include/pystate.h
index 7b6b602..c0f493b 100644
--- a/Include/pystate.h
+++ b/Include/pystate.h
@@ -112,6 +112,7 @@ PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_New(void);
 PyAPI_FUNC(void) PyInterpreterState_Clear(PyInterpreterState *);
 PyAPI_FUNC(void) PyInterpreterState_Delete(PyInterpreterState *);
 PyAPI_FUNC(int) _PyState_AddModule(PyObject*, struct PyModuleDef*);
+PyAPI_FUNC(void) _PyState_ClearModules(void);
 PyAPI_FUNC(PyObject*) PyState_FindModule(struct PyModuleDef*);
 
 PyAPI_FUNC(PyThreadState *) PyThreadState_New(PyInterpreterState *);
diff --git a/Python/import.c b/Python/import.c
index 523a1c0..d60566d 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -463,6 +463,9 @@ PyImport_Cleanup(void)
         PyDict_SetItemString(modules, "__main__", Py_None);
     }
 
+    /* cleanup module dict copies stored in the interpreter state */
+    _PyState_ClearModules();
+
     /* The special treatment of "builtins" here is because even
        when it's not referenced as a module, its dictionary is
        referenced by almost every module's __builtins__.  Since
diff --git a/Python/pystate.c b/Python/pystate.c
index d5d98b0..975e20f 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -267,6 +267,26 @@ _PyState_AddModule(PyObject* module, struct PyModuleDef* def)
                           def->m_base.m_index, module);
 }
 
+/* used by import.c:PyImport_Cleanup */
+void
+_PyState_ClearModules(void)
+{
+    PyInterpreterState *state = PyThreadState_GET()->interp;
+    if (state->modules_by_index) {
+        Py_ssize_t i;
+        for (i = 0; i < PyList_GET_SIZE(state->modules_by_index); i++) {
+            PyObject *m = PyList_GET_ITEM(state->modules_by_index, i);
+            if (PyModule_Check(m)) {
+                /* cleanup copy of module dicts */
+                PyModuleDef *md = PyModule_GetDef(m);
+                if (md)
+                    Py_CLEAR(md->m_base.m_copy);
+            }
+        }
+        Py_CLEAR(state->modules_by_index);
+    }
+}
+
 void
 PyThreadState_Clear(PyThreadState *tstate)
 {