diff --git a/test/open-uri/test_ssl.rb b/test/open-uri/test_ssl.rb
index dfa3283486..389391e685 100644
--- a/test/open-uri/test_ssl.rb
+++ b/test/open-uri/test_ssl.rb
@@ -50,7 +50,7 @@ class TestOpenURISSL < Test::Unit::TestCase
   end
 
   def test_validation_failure
-    with_https(nil) {|srv, dr, url, server_thread, server_log|
+    with_https(nil) {|srv, dr, url|
       setup_validation(srv, dr)
       assert_raise(OpenSSL::SSL::SSLError) { URI.open("#{url}/data") {} }
       sleep 0.5 unless RUBY_PLATFORM =~ /mswin|mingw/
diff --git a/test/open-uri/utils.rb b/test/open-uri/utils.rb
index 36d00e7932..e7ca64bd1c 100644
--- a/test/open-uri/utils.rb
+++ b/test/open-uri/utils.rb
@@ -343,7 +343,7 @@ module TestOpenURIUtils
   def with_https_proxy(proxy_log_tester=lambda {|proxy_log, proxy_access_log| assert_equal([], proxy_log) })
     proxy_log = []
     proxy_access_log = []
-    with_https {|srv, dr, url, server_thread, server_log, threads|
+    with_https {|srv, dr, url|
       srv.instance_variable_get(:@server).setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, true)
       cacert_filename = "#{dr}/cacert.pem"
       open(cacert_filename, "w") {|f| f << CA_CERT }
@@ -355,7 +355,7 @@ module TestOpenURIUtils
       proxy = SimpleHTTPProxyServer.new(proxy_host, 0, proxy_log, proxy_access_log)
       proxy_port = proxy.instance_variable_get(:@server).addr[1]
       proxy_thread = proxy.start
-      threads << Thread.new {
+      thread = Thread.new {
         proxy_thread.join
         if proxy_log_tester
           proxy_log_tester.call(proxy_log, proxy_access_log)
@@ -367,6 +367,7 @@ module TestOpenURIUtils
       ensure
         proxy.shutdown
       end
+      assert_join_threads([thread])
     }
   end
 
@@ -390,7 +391,7 @@ module TestOpenURIUtils
       }
       threads << Thread.new {
         begin
-          yield srv, dr, "https://#{host}:#{port}", server_thread, log, threads
+          yield srv, dr, "https://#{host}:#{port}"
         ensure
           srv.shutdown
         end