diff --git a/ChangeLog b/ChangeLog
index 8698b396d7..67c0d1fbae 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jul  5 16:05:39 2010  Akinori MUSHA  <knu@iDaemons.org>
+
+	* vm_method.c (rb_method_boundp): Return false for protected
+	  methods when called from Kernel#respond_to?. [ruby-dev:40461]
+
 Mon Jul  5 12:32:01 2010  Aaron Patterson <aaron@tenderlovemaking.com>
 
 	* ext/psych/lib/psych/scalar_scanner.rb (parse_string): support
diff --git a/NEWS b/NEWS
index ab1e9c0edd..9c2fc05c90 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,21 @@ Note that each entry is kept so brief that no reason behind or
 reference information is supplied with.  For a full list of changes
 with all sufficient information, see the ChangeLog file.
 
+== Changes since the 1.9.2 release
+=== Library updates (outstanding ones only)
+
+* builtin classes
+
+  * Kernel
+
+    * Kernel#respond_to? now returns false for protected methods.
+
+=== Compatibility issues (excluding feature bug fixes)
+
+* Kernel#respond_to?
+
+  See above.
+
 == Changes since the 1.9.1 release
 === Library updates (outstanding ones only)
 
diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index 7be70b00a6..61f523e4e1 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -39,6 +39,20 @@ class TestMethod < Test::Unit::TestCase
     def meth; end
   end
 
+  def mv1() end
+  def mv2() end
+  private :mv2
+  def mv3() end
+  protected :mv3
+
+  class Visibility
+    def mv1() end
+    def mv2() end
+    private :mv2
+    def mv3() end
+    protected :mv3
+  end
+
   def test_arity
     assert_equal(0, method(:m0).arity)
     assert_equal(1, method(:m1).arity)
@@ -345,4 +359,48 @@ class TestMethod < Test::Unit::TestCase
     obj.extend(m)
     assert_equal([:m1, :a], obj.public_methods(false), bug)
   end
+
+  def test_visibility
+    assert_equal('method', defined?(mv1))
+    assert_equal('method', defined?(mv2))
+    assert_equal('method', defined?(mv3))
+
+    assert_equal('method', defined?(self.mv1))
+    assert_equal(nil, defined?(self.mv2))
+    assert_equal('method', defined?(self.mv3))
+
+    assert_equal(true,  respond_to?(:mv1))
+    assert_equal(false, respond_to?(:mv2))
+    assert_equal(false, respond_to?(:mv3))
+
+    assert_nothing_raised { mv1 }
+    assert_nothing_raised { mv2 }
+    assert_nothing_raised { mv3 }
+
+    assert_nothing_raised { self.mv1 }
+    assert_raise(NoMethodError) { self.mv2 }
+    assert_nothing_raised { self.mv3 }
+
+    v = Visibility.new
+
+    assert_equal('method', defined?(v.mv1))
+    assert_equal(nil, defined?(v.mv2))
+    assert_equal(nil, defined?(v.mv3))
+
+    assert_equal(true,  v.respond_to?(:mv1))
+    assert_equal(false, v.respond_to?(:mv2))
+    assert_equal(false, v.respond_to?(:mv3))
+
+    assert_nothing_raised { v.mv1 }
+    assert_raise(NoMethodError) { v.mv2 }
+    assert_raise(NoMethodError) { v.mv3 }
+
+    assert_nothing_raised { v.__send__(:mv1) }
+    assert_nothing_raised { v.__send__(:mv2) }
+    assert_nothing_raised { v.__send__(:mv3) }
+
+    assert_nothing_raised { v.instance_eval { mv1 } }
+    assert_nothing_raised { v.instance_eval { mv2 } }
+    assert_nothing_raised { v.instance_eval { mv3 } }
+  end
 end
diff --git a/vm_method.c b/vm_method.c
index 50f0b12e5a..becce27c1c 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -566,8 +566,9 @@ rb_method_boundp(VALUE klass, ID id, int ex)
     rb_method_entry_t *me = rb_method_entry(klass, id);
 
     if (me != 0) {
-	if ((ex & ~NOEX_RESPONDS) && (me->flag & NOEX_PRIVATE)) {
-	    return FALSE;
+	if ((ex &  NOEX_RESPONDS) && (me->flag & NOEX_PROTECTED) ||
+	    (ex & ~NOEX_RESPONDS) && (me->flag & NOEX_PRIVATE)) {
+	    return 0;
 	}
 	if (!me->def) return 0;
 	if (me->def->type == VM_METHOD_TYPE_NOTIMPLEMENTED) {