diff --git a/test/webrick/test_httpresponse.rb b/test/webrick/test_httpresponse.rb
index 1a2bc3e0..722588da 100644
--- a/test/webrick/test_httpresponse.rb
+++ b/test/webrick/test_httpresponse.rb
@@ -290,6 +290,8 @@ def test_send_body_proc_stream
         chunk = s2.read
         assert_match /Connection: close\r\n\r\nhello/, chunk
         s2.close
+
+        thread.join
       end
       assert_empty logger.messages
     end