diff --git a/activesupport/lib/active_support/core_ext/object/json.rb b/activesupport/lib/active_support/core_ext/object/json.rb
index d49b2fbe546..32a41eafe43 100644
--- a/activesupport/lib/active_support/core_ext/object/json.rb
+++ b/activesupport/lib/active_support/core_ext/object/json.rb
@@ -1,6 +1,7 @@
 # Hack to load json gem first so we can overwrite its to_json.
 require 'json'
 require 'bigdecimal'
+require 'uri/generic'
 require 'active_support/core_ext/big_decimal/conversions' # for #to_s
 require 'active_support/core_ext/hash/except'
 require 'active_support/core_ext/hash/slice'
@@ -192,6 +193,12 @@ class DateTime
   end
 end
 
+class URI::Generic #:nodoc:
+  def as_json(options = nil)
+    to_s
+  end
+end
+
 class Process::Status #:nodoc:
   def as_json(options = nil)
     { :exitstatus => exitstatus, :pid => pid }
diff --git a/activesupport/test/json/encoding_test_cases.rb b/activesupport/test/json/encoding_test_cases.rb
index 0159ba86063..60d8685d327 100644
--- a/activesupport/test/json/encoding_test_cases.rb
+++ b/activesupport/test/json/encoding_test_cases.rb
@@ -76,6 +76,8 @@ module JSONTest
 
     RegexpTests   = [[ /^a/, '"(?-mix:^a)"' ], [/^\w{1,2}[a-z]+/ix, '"(?ix-m:^\\\\w{1,2}[a-z]+)"']]
 
+    URITests      = [[ URI.parse('http://example.com'), %("http://example.com") ]]
+
     DateTests     = [[ Date.new(2005,2,1), %("2005/02/01") ]]
     TimeTests     = [[ Time.utc(2005,2,1,15,15,10), %("2005/02/01 15:15:10 +0000") ]]
     DateTimeTests = [[ DateTime.civil(2005,2,1,15,15,10), %("2005/02/01 15:15:10 +0000") ]]