diff --git a/ChangeLog b/ChangeLog
index 257fe7a321..95a87063d5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Mon Oct 26 22:43:03 2015  yui-knk  <spiketeika@gmail.com>
+
+	* test/ruby/test_module.rb (test_method_defined): Add test cases
+	  for `public/protected/private _method_defined?`
+	  These methods accept string as argument, so add string argument
+	  cases.  [Fix GH-1067]
+
 Mon Oct 26 22:23:30 2015  SimonDKnight  <simondknight@hotmail.com>
 
 	* lib/racc/rdoc/grammar.en.rdoc: Grammatical errors fixed.
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 9b5cbfee88..ed052ff711 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -964,13 +964,28 @@ class TestModule < Test::Unit::TestCase
     assert_equal(false, c.public_method_defined?(:bar))
     assert_equal(false, c.public_method_defined?(:baz))
 
+    # Test if string arguments are converted to symbols
+    assert_equal(true, c.public_method_defined?("foo"))
+    assert_equal(false, c.public_method_defined?("bar"))
+    assert_equal(false, c.public_method_defined?("baz"))
+
     assert_equal(false, c.protected_method_defined?(:foo))
     assert_equal(true, c.protected_method_defined?(:bar))
     assert_equal(false, c.protected_method_defined?(:baz))
 
+    # Test if string arguments are converted to symbols
+    assert_equal(false, c.protected_method_defined?("foo"))
+    assert_equal(true, c.protected_method_defined?("bar"))
+    assert_equal(false, c.protected_method_defined?("baz"))
+
     assert_equal(false, c.private_method_defined?(:foo))
     assert_equal(false, c.private_method_defined?(:bar))
     assert_equal(true, c.private_method_defined?(:baz))
+
+    # Test if string arguments are converted to symbols
+    assert_equal(false, c.private_method_defined?("foo"))
+    assert_equal(false, c.private_method_defined?("bar"))
+    assert_equal(true, c.private_method_defined?("baz"))
   end
 
   def test_top_public_private