diff --git a/t/iolua.lua b/t/iolua.lua
index da453b22..193cd547 100644
--- a/t/iolua.lua
+++ b/t/iolua.lua
@@ -95,3 +95,5 @@ if rest == "AHAHA\nIHIHI\nUFUFU\n" then
 else
     print("NG: read('*a'):["..rest.."]")
 end
+
+io.stdout:setvbuf("no")