diff --git a/ChangeLog b/ChangeLog
index a638367810..d3743ae83c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Dec 25 12:44:27 2008  Koichi Sasada  <ko1@atdot.net>
+
+	* vm_insnhelper.c (vm_yield_with_cfunc): check block has Proc.
+
 Thu Dec 25 05:53:01 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* template/id.h.tmpl, id.h (ruby_method_ids): not depend on if
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 46c11a6de0..13bd03dc66 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -661,7 +661,12 @@ vm_yield_with_cfunc(rb_thread_t *th, const rb_block_t *block,
     }
 
     if (blockptr) {
-	blockarg = vm_make_proc(th, blockptr, rb_cProc);
+	if (blockptr->proc) {
+	    blockarg = blockptr->proc;
+	}
+	else {
+	    blockarg = vm_make_proc(th, blockptr, rb_cProc);
+	}
     }
     else {
 	blockarg = Qnil;