diff --git a/lib/net/http.rb b/lib/net/http.rb
index 0fec32bb84..90f299f705 100644
--- a/lib/net/http.rb
+++ b/lib/net/http.rb
@@ -1612,11 +1612,10 @@ module Net   #:nodoc:
     private
 
     def addr_port
-      if use_ssl?
-        address() + (port == HTTP.https_default_port ? '' : ":#{port()}")
-      else
-        address() + (port == HTTP.http_default_port ? '' : ":#{port()}")
-      end
+      addr = address
+      addr = "[#{addr}]" if addr.include?(":")
+      default_port = use_ssl? ? HTTP.https_default_port : HTTP.http_default_port
+      default_port == port ? addr : "#{addr}:#{port}"
     end
 
     def D(msg)
diff --git a/test/net/http/test_http.rb b/test/net/http/test_http.rb
index c5a77d3695..d3c2aecb9f 100644
--- a/test/net/http/test_http.rb
+++ b/test/net/http/test_http.rb
@@ -59,6 +59,33 @@ class TestNetHTTP < Test::Unit::TestCase
     end
   end
 
+  def test_addr_port
+    http = Net::HTTP.new 'hostname.example', nil, nil
+    addr_port = http.__send__ :addr_port
+    assert_equal 'hostname.example', addr_port
+
+    http.use_ssl = true
+    addr_port = http.__send__ :addr_port
+    assert_equal 'hostname.example:80', addr_port
+
+    http = Net::HTTP.new '203.0.113.1', nil, nil
+    addr_port = http.__send__ :addr_port
+    assert_equal '203.0.113.1', addr_port
+
+    http.use_ssl = true
+    addr_port = http.__send__ :addr_port
+    assert_equal '203.0.113.1:80', addr_port
+
+    http = Net::HTTP.new '2001:db8::1', nil, nil
+    addr_port = http.__send__ :addr_port
+    assert_equal '[2001:db8::1]', addr_port
+
+    http.use_ssl = true
+    addr_port = http.__send__ :addr_port
+    assert_equal '[2001:db8::1]:80', addr_port
+
+  end
+
   def test_edit_path
     http = Net::HTTP.new 'hostname.example', nil, nil