diff --git a/Modules/main.c b/Modules/main.c
index 4d2e03a..3cfc9c3 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -77,7 +77,8 @@
 -S     : don't imply 'import site' on initialization\n\
 ";
 static char *usage_3 = "\
--u     : unbuffered binary stdout and stderr; also PYTHONUNBUFFERED=x\n\
+-u     : unbuffered binary stdout and stderr, stdin always buffered;\n\
+         also PYTHONUNBUFFERED=x\n\
          see man page for details on internal buffering relating to '-u'\n\
 -v     : verbose (trace import statements); also PYTHONVERBOSE=x\n\
          can be supplied multiple times to increase verbosity\n\