diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 1ee062f..39c86e7 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1242,7 +1242,10 @@
 	if (exception == NULL)
 		return;
 	PyErr_NormalizeException(&exception, &v, &tb);
-	tb = tb ? tb : Py_None;
+	if (tb == NULL) {
+		tb = Py_None;
+		Py_INCREF(tb);
+	}
 	PyException_SetTraceback(v, tb);
 	if (exception == NULL)
 		return;