diff --git a/ChangeLog b/ChangeLog
index 9afdea8d41..fea0b9ac39 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Dec 26 17:20:10 2011  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* vm.c (vm_exec): add guard to prevent optimization for LLVM clang.
+
 Fri Dec 30 17:01:12 2011  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
 
 	* vm_eval.c (rb_f_send): fix iobj.send() documentation issue.
diff --git a/vm.c b/vm.c
index 67ca4393a5..2f38eeef2e 100644
--- a/vm.c
+++ b/vm.c
@@ -1216,6 +1216,9 @@ vm_exec(rb_thread_t *th)
       vm_loop_start:
 	result = vm_exec_core(th, initial);
 	if ((state = th->state) != 0) {
+#ifdef __llvm__
+	    rb_thread_t t = *th;
+#endif
 	    err = result;
 	    th->state = 0;
 	    goto exception_handler;