diff --git a/ChangeLog b/ChangeLog
index 91c4fc672f..7093ce4ca2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Nov  6 23:36:07 2016  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* test/ruby/test_optimization.rb (test_tailcall_interrupted_by_sigint):
+	  send SIGKILL if the child process doesn't die within 1 second.
+
 Sun Nov  6 21:54:28 2016  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* tool/vcs.rb (export_changelog): generate ChangeLog file from
diff --git a/test/ruby/test_optimization.rb b/test/ruby/test_optimization.rb
index 6f5262a69d..0205c92e2f 100644
--- a/test/ruby/test_optimization.rb
+++ b/test/ruby/test_optimization.rb
@@ -338,9 +338,21 @@ EOS
       in_p.write(script)
       in_p.close
       out_p.gets
-      Process.kill(:SIGINT, pid)
-      *, stat = Process.wait2(pid)
-      [stat, err_p.read]
+      sig = :INT
+      begin
+        Process.kill(sig, pid)
+        Timeout.timeout(1) do
+          *, stat = Process.wait2(pid)
+          [stat, err_p.read]
+        end
+      rescue Timeout::Error
+        if sig == :INT
+          sig = :KILL
+          retry
+        else
+          raise
+        end
+      end
     }
     assert_equal("INT", Signal.signame(status.termsig))
     assert_match(/Interrupt/, err, bug)