diff --git a/ChangeLog b/ChangeLog
index 41ca7b8648..dd3c1f767a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Oct 17 11:27:44 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* vm_method.c (basic_obj_respond_to): call #respond_to_missing?
+	  always with two arguments.  [ruby-core:26090]
+
 Sat Oct 17 08:51:44 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* lib/delegate.rb (Delegator#respond_to_missing): warn only when
diff --git a/lib/delegate.rb b/lib/delegate.rb
index 6bee43293e..9ce3aee81e 100644
--- a/lib/delegate.rb
+++ b/lib/delegate.rb
@@ -148,7 +148,7 @@ class Delegator
   # Checks for a method provided by this the delegate object by forwarding the
   # call through \_\_getobj\_\_.
   #
-  def respond_to_missing?(m, include_private = false)
+  def respond_to_missing?(m, include_private)
     r = self.__getobj__.respond_to?(m, include_private)
     if r && include_private && !self.__getobj__.respond_to?(m, false)
       warn "#{caller(3)[0]}: delegator does not forward private method \##{m}"
diff --git a/vm_method.c b/vm_method.c
index bed8e61bd6..557583f5aa 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -1157,7 +1157,7 @@ basic_obj_respond_to(VALUE obj, ID id, int pub)
       case 2:
 	return FALSE;
       case 0:
-	return RTEST(rb_funcall(obj, respond_to_missing, pub ? 1 : 2, ID2SYM(id), Qtrue));
+	return RTEST(rb_funcall(obj, respond_to_missing, 2, ID2SYM(id), pub ? Qfalse : Qtrue));
       default:
 	return TRUE;
     }
@@ -1214,7 +1214,7 @@ obj_respond_to(int argc, VALUE *argv, VALUE obj)
 
 /*
  *  call-seq:
- *     obj.respond_to_missing?(symbol, include_private=false) => true or false
+ *     obj.respond_to_missing?(symbol, include_private) => true or false
  *
  *  Hook method to return whether the _obj_ can respond to _id_ method
  *  or not.
@@ -1222,7 +1222,7 @@ obj_respond_to(int argc, VALUE *argv, VALUE obj)
  *  See #respond_to?.
  */
 static VALUE
-obj_respond_to_missing(int argc, VALUE *argv, VALUE obj)
+obj_respond_to_missing(VALUE obj, VALUE priv)
 {
     return Qfalse;
 }
@@ -1234,7 +1234,7 @@ Init_eval_method(void)
 #define rb_intern(str) rb_intern_const(str)
 
     rb_define_method(rb_mKernel, "respond_to?", obj_respond_to, -1);
-    rb_define_method(rb_mKernel, "respond_to_missing?", obj_respond_to_missing, -1);
+    rb_define_method(rb_mKernel, "respond_to_missing?", obj_respond_to_missing, 2);
 
     rb_define_private_method(rb_cModule, "remove_method", rb_mod_remove_method, -1);
     rb_define_private_method(rb_cModule, "undef_method", rb_mod_undef_method, -1);