diff --git a/ChangeLog b/ChangeLog
index 5615c44c5f..7c63a77cf3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Tue Dec 29 10:35:00 2015  Kenta Murata  <mrkn@mrkn.jp>
+
+	* test/mkmf/test_have_func.rb (test_have_func):
+	  Add assertion to examine the existence of HAVE_RUBY_INIT.
+
+	* test/mkmf/test_have_func.rb (test_not_have_func):
+	  Add assertion to examine the absence of HAVE_RUBY_INIT.
+
 Tue Dec 29 06:50:42 2015  Eric Wong  <e@80x24.org>
 
 	* thread_sync.c: static classes
diff --git a/test/mkmf/test_have_func.rb b/test/mkmf/test_have_func.rb
index 5f76b72122..6204ab24f0 100644
--- a/test/mkmf/test_have_func.rb
+++ b/test/mkmf/test_have_func.rb
@@ -6,10 +6,12 @@ class TestMkmf
   class TestHaveFunc < TestMkmf
     def test_have_func
       assert_equal(true, have_func("ruby_init"), MKMFLOG)
+      assert_include($defs, '-DHAVE_RUBY_INIT')
     end
 
     def test_not_have_func
       assert_equal(false, have_func("no_ruby_init"), MKMFLOG)
+      assert_not_include($defs, '-DHAVE_RUBY_INIT')
     end
   end
 end