diff --git a/test/net/http/test_http.rb b/test/net/http/test_http.rb
index 4d82fd7..187f94b 100644
--- a/test/net/http/test_http.rb
+++ b/test/net/http/test_http.rb
@@ -1,10 +1,10 @@
 # coding: US-ASCII
-require 'test/unit'
+require 'minitest/autorun'
 require 'net/http'
 require 'stringio'
 require_relative 'utils'
 
-class TestNetHTTP < Test::Unit::TestCase
+class TestNetHTTP < MiniTest::Unit::TestCase
 
   def test_class_Proxy
     no_proxy_class = Net::HTTP.Proxy nil
@@ -189,12 +189,14 @@ class TestNetHTTP < Test::Unit::TestCase
   end
 
   def test_failure_message_includes_failed_domain_and_port
-    begin
-      Net::HTTP.get(URI.parse("http://doesnotexist.bogus"))
-      fail "should have raised"
-    rescue => e
-      assert_includes e.message, "doesnotexist.bogus:80"
+    e = assert_raises(RuntimeError) do
+      dns_lookup_failure_message = "SocketError: getaddrinfo: Name or service not known"
+      socket_open_failure = ->(_, _, _, _) { raise dns_lookup_failure_message }
+      TCPSocket.stub :open, socket_open_failure do
+        Net::HTTP.get(URI.parse("http://doesnotexist.bogus"))
+      end
     end
+    assert_includes e.message, "doesnotexist.bogus:80"
   end
 
 end