diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 337518c5042a..b412c62486f0 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -95,6 +95,8 @@ static int start_ptraced_child(void)
 {
 	int pid, n, status;
 
+	fflush(stdout);
+
 	pid = fork();
 	if (pid == 0)
 		ptrace_child();