diff --git a/code/userprog/exception.cc b/code/userprog/exception.cc
index 7dc3e42..df7ca0e 100644
--- a/code/userprog/exception.cc
+++ b/code/userprog/exception.cc
@@ -131,6 +131,8 @@ ExceptionHandler (ExceptionType which)
         #ifdef CHANGED
         case SC_Exit:
           {
+            while (1)
+                currentThread->Yield();
             int ret = machine->ReadRegister(4);
             printf("Exit code %d\n", ret);
             interrupt->Powerdown();