diff --git a/cmd/tools/test_os_process.v b/cmd/tools/test_os_process.v
index 3eecbc0a5b..7424120202 100644
--- a/cmd/tools/test_os_process.v
+++ b/cmd/tools/test_os_process.v
@@ -51,6 +51,7 @@ fn do_timeout(c &Context) {
 }
 
 fn main() {
+	unbuffer_stdout()
 	mut ctx := Context{}
 	args := os.args[1..]
 	if '-h' in args || '--help' in args {