diff --git a/ChangeLog b/ChangeLog
index 6e0a6e95c3..20e480fe08 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Thu Oct 15 01:57:03 2015  CHIKANAGA Tomoyuki  <nagachika@ruby-lang.org>
+
+	* test/objspace/test_objspace.rb
+	  (test_trace_object_allocations_start_stop_clear): clear object
+	  allocation table first to get rid of erronous detection for obj3.
+	  [ruby-dev:49095] [Bug #11271]
+
 Thu Oct 15 01:53:38 2015  Benoit Daloze  <eregontp@gmail.com>
 
 	* test/ostruct/test_ostruct.rb: Add tests for OpenStruct#respond_to.
diff --git a/test/objspace/test_objspace.rb b/test/objspace/test_objspace.rb
index 2acc35469f..820edc7a20 100644
--- a/test/objspace/test_objspace.rb
+++ b/test/objspace/test_objspace.rb
@@ -177,6 +177,8 @@ class TestObjSpace < Test::Unit::TestCase
   end
 
   def test_trace_object_allocations_start_stop_clear
+    ObjectSpace.trace_object_allocations_clear # clear object_table to get rid of erronous detection for obj3
+    GC.disable # suppress potential object reuse. see [Bug #11271]
     begin
       ObjectSpace.trace_object_allocations_start
       begin
@@ -207,6 +209,8 @@ class TestObjSpace < Test::Unit::TestCase
     assert_equal(nil, ObjectSpace.allocation_sourcefile(obj1))
     assert_equal(nil, ObjectSpace.allocation_sourcefile(obj2))
     assert_equal(nil, ObjectSpace.allocation_sourcefile(obj3))
+  ensure
+    GC.enable
   end
 
   def test_dump_flags