diff --git a/ChangeLog b/ChangeLog
index 7a82244201..23394ccd1c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Jul 19 15:38:59 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* variable.c (rb_local_constants_i): exclude private constants
+	  when excluding inherited constants too.  [Bug #12345]
+
 Sun Jul 17 23:42:00 2016  Kenta Murata  <mrkn@mrkn.jp>
 
 	* numeric.c (num_finite_p, num_infinite_p): Add Numeric#finite? and
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 92c3dfd6eb..0f9351c57d 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -1423,6 +1423,8 @@ class TestModule < Test::Unit::TestCase
 
   def test_constants_with_private_constant
     assert_not_include(::TestModule.constants, :PrivateClass)
+    assert_not_include(::TestModule.constants(true), :PrivateClass)
+    assert_not_include(::TestModule.constants(false), :PrivateClass)
   end
 
   def test_toplevel_private_constant
diff --git a/variable.c b/variable.c
index 4d3222b5db..0966685690 100644
--- a/variable.c
+++ b/variable.c
@@ -2399,7 +2399,7 @@ sv_i(ID key, VALUE v, void *a)
 static enum rb_id_table_iterator_result
 rb_local_constants_i(ID const_name, VALUE const_value, void *ary)
 {
-    if (rb_is_const_id(const_name)) {
+    if (rb_is_const_id(const_name) && !RB_CONST_PRIVATE_P((rb_const_entry_t *)const_value)) {
 	rb_ary_push((VALUE)ary, ID2SYM(const_name));
     }
     return ID_TABLE_CONTINUE;