diff --git a/Python/frozenmain.c b/Python/frozenmain.c
index 755033c9ba5..10fba54ce94 100644
--- a/Python/frozenmain.c
+++ b/Python/frozenmain.c
@@ -51,6 +51,7 @@ Py_FrozenMain(argc, argv)
 		unbuffered = 1;
 
 	if (unbuffered) {
+		setbuf(stdin, (char *)NULL);
 		setbuf(stdout, (char *)NULL);
 		setbuf(stderr, (char *)NULL);
 	}