diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index db5d0a7..7f63ae1 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1149,7 +1149,7 @@
         PySys_SetObject("last_traceback", tb);
     }
     hook = PySys_GetObject("excepthook");
-    if (hook) {
+    if (hook && hook != Py_None) {
         PyObject *args = PyTuple_Pack(3,
             exception, v, tb ? tb : Py_None);
         PyObject *result = PyEval_CallObject(hook, args);
@@ -1199,7 +1199,7 @@
     int err = 0;
     PyObject *f = PySys_GetObject("stderr");
     Py_INCREF(value);
-    if (f == NULL)
+    if (f == NULL || f == Py_None)
         fprintf(stderr, "lost sys.stderr\n");
     else {
         if (Py_FlushLine())