diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index f72c9d7..fe99fd2 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -255,7 +255,7 @@
     bimod = _PyBuiltin_Init();
     if (bimod == NULL)
         Py_FatalError("Py_Initialize: can't initialize builtins modules");
-    _PyImport_FixupExtension(bimod, "builtins", "builtins");
+    _PyImport_FixupBuiltin(bimod, "builtins");
     interp->builtins = PyModule_GetDict(bimod);
     if (interp->builtins == NULL)
         Py_FatalError("Py_Initialize: can't initialize builtins dict");
@@ -271,7 +271,7 @@
     if (interp->sysdict == NULL)
         Py_FatalError("Py_Initialize: can't initialize sys dict");
     Py_INCREF(interp->sysdict);
-    _PyImport_FixupExtension(sysmod, "sys", "sys");
+    _PyImport_FixupBuiltin(sysmod, "sys");
     PySys_SetPath(Py_GetPath());
     PyDict_SetItemString(interp->sysdict, "modules",
                          interp->modules);
@@ -577,7 +577,7 @@
     interp->modules = PyDict_New();
     interp->modules_reloading = PyDict_New();
 
-    bimod = _PyImport_FindExtension("builtins", "builtins");
+    bimod = _PyImport_FindBuiltin("builtins");
     if (bimod != NULL) {
         interp->builtins = PyModule_GetDict(bimod);
         if (interp->builtins == NULL)
@@ -588,7 +588,7 @@
     /* initialize builtin exceptions */
     _PyExc_Init();
 
-    sysmod = _PyImport_FindExtension("sys", "sys");
+    sysmod = _PyImport_FindBuiltin("sys");
     if (bimod != NULL && sysmod != NULL) {
         PyObject *pstderr;
         interp->sysdict = PyModule_GetDict(sysmod);