diff --git a/ChangeLog b/ChangeLog
index 6fe7d64c60..c9ddb12f8e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri May 27 17:38:49 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* variable.c (rb_local_constants_i): exclude hidden constants.
+	  [ruby-core:75575] [Bug #12389]
+
 Fri May 27 17:09:44 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* transcode.c (str_transcode0): scrub in the given encoding when
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 65e6a2c4c4..92c3dfd6eb 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -603,6 +603,8 @@ class TestModule < Test::Unit::TestCase
       const_set(:X, 123)
     end
     assert_equal(false, klass.class_eval { Module.constants }.include?(:X))
+
+    assert_equal(false, Complex.constants(false).include?(:compatible))
   end
 
   module M1
diff --git a/variable.c b/variable.c
index db26268cfa..849be3abaa 100644
--- a/variable.c
+++ b/variable.c
@@ -2388,7 +2388,9 @@ 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)
 {
-    rb_ary_push((VALUE)ary, ID2SYM(const_name));
+    if (rb_is_const_id(const_name)) {
+	rb_ary_push((VALUE)ary, ID2SYM(const_name));
+    }
     return ID_TABLE_CONTINUE;
 }