diff --git a/ChangeLog b/ChangeLog
index afe79b1f34..ff62008f2e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Oct 15 09:41:17 2012  Koichi Sasada  <ko1@atdot.net>
+
+	* vm_insnhelper.c (VM_CALLEE_SETUP_ARG): skip CI_SET_FASTPATH() if
+	  it was called from vm_yield_setup_args().
+
 Mon Oct 15 05:20:13 2012  Koichi Sasada  <ko1@atdot.net>
 
 	* vm_insnhelper.h CI_SET_FASTPATH: introduce new macro
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 6866409992..5c50deaa38 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -1176,14 +1176,14 @@ vm_callee_setup_arg_complex(rb_thread_t *th, rb_call_info_t *ci, const rb_iseq_t
 
 static VALUE vm_call_iseq_setup_2(rb_thread_t *th, rb_control_frame_t *cfp, rb_call_info_t *ci);
 
-#define VM_CALLEE_SETUP_ARG(th, ci, iseq, argv) \
+#define VM_CALLEE_SETUP_ARG(th, ci, iseq, argv, is_lambda) \
     if (LIKELY((iseq)->arg_simple & 0x01)) { \
 	/* simple check */ \
 	if ((ci)->argc != (iseq)->argc) { \
 	    argument_error((iseq), ((ci)->argc), (iseq)->argc, (iseq)->argc); \
 	} \
 	(ci)->opt_pc = 0; \
-	CI_SET_FASTPATH((ci), vm_call_iseq_setup_2); \
+	if (!is_lambda) CI_SET_FASTPATH((ci), vm_call_iseq_setup_2); \
     } \
     else { \
 	(ci)->opt_pc = vm_callee_setup_arg_complex((th), (ci), (iseq), (argv)); \
@@ -1192,7 +1192,7 @@ static VALUE vm_call_iseq_setup_2(rb_thread_t *th, rb_control_frame_t *cfp, rb_c
 static VALUE
 vm_call_iseq_setup(rb_thread_t *th, rb_control_frame_t *cfp, rb_call_info_t *ci)
 {
-    VM_CALLEE_SETUP_ARG(th, ci, ci->me->def->body.iseq, cfp->sp - ci->argc);
+    VM_CALLEE_SETUP_ARG(th, ci, ci->me->def->body.iseq, cfp->sp - ci->argc, 0);
     return vm_call_iseq_setup_2(th, cfp, ci);
 }
 
@@ -1955,7 +1955,7 @@ vm_yield_setup_args(rb_thread_t * const th, const rb_iseq_t *iseq,
 	ci_entry.flag = 0;
 	ci_entry.argc = argc;
 	ci_entry.blockptr = (rb_block_t *)blockptr;
-	VM_CALLEE_SETUP_ARG(th, &ci_entry, iseq, argv);
+	VM_CALLEE_SETUP_ARG(th, &ci_entry, iseq, argv, 1);
 	return ci_entry.opt_pc;
     }
     else {