diff --git a/ucore/src/exit.c b/ucore/src/exit.c
index c3ac5f8..d72c05e 100644
--- a/ucore/src/exit.c
+++ b/ucore/src/exit.c
@@ -24,8 +24,8 @@ main(void) {
     assert(pid > 0);
     cprintf("I am the parent, waiting now..\n");
 
-    assert(waitpid(pid, &code) == 0 && code == magic);
-    assert(waitpid(pid, &code) != 0 && wait() != 0);
+    assert(waitpid(pid, &code) > 0 && code == magic);
+    assert(waitpid(pid, &code) <= 0 && wait() <= 0);
     cprintf("waitpid %d ok.\n", pid);
 
     cprintf("exit pass.\n");