diff --git a/lib/twitter_auth/dispatcher/basic.rb b/lib/twitter_auth/dispatcher/basic.rb
index bcfbb08..749321d 100644
--- a/lib/twitter_auth/dispatcher/basic.rb
+++ b/lib/twitter_auth/dispatcher/basic.rb
@@ -13,7 +13,7 @@ def initialize(user)
       end
 
       def request(http_method, path, body=nil, *arguments)
-        path << '.json' unless path.match(/\.(:?xml|json)\z/i)
+        path = append_extension_to(path)
 
         response = TwitterAuth.net.start{ |http|
           req = "Net::HTTP::#{http_method.to_s.capitalize}".constantize.new(path, *arguments)
diff --git a/lib/twitter_auth/dispatcher/oauth.rb b/lib/twitter_auth/dispatcher/oauth.rb
index ca18742..859d2ae 100644
--- a/lib/twitter_auth/dispatcher/oauth.rb
+++ b/lib/twitter_auth/dispatcher/oauth.rb
@@ -14,7 +14,8 @@ def initialize(user)
       end
 
       def request(http_method, path, *arguments)
-        path << '.json' unless path.match(/\.(:?xml|json)\z/i)
+        path = append_extension_to(path)
+       
         response = super
 
         handle_response(response)
diff --git a/lib/twitter_auth/dispatcher/shared.rb b/lib/twitter_auth/dispatcher/shared.rb
index 4bc36a2..a777c3e 100644
--- a/lib/twitter_auth/dispatcher/shared.rb
+++ b/lib/twitter_auth/dispatcher/shared.rb
@@ -1,6 +1,12 @@
 module TwitterAuth
   module Dispatcher
     module Shared
+      def append_extension_to(path)
+        path, query_string = *(path.split("?"))
+        path << '.json' unless path.match(/\.(:?xml|json)\z/i)
+        "#{path}#{"?#{query_string}" if query_string}"
+      end
+
       def handle_response(response)
         case response
         when Net::HTTPOK 
diff --git a/spec/twitter_auth/dispatcher/shared_spec.rb b/spec/twitter_auth/dispatcher/shared_spec.rb
new file mode 100644
index 0000000..af31555
--- /dev/null
+++ b/spec/twitter_auth/dispatcher/shared_spec.rb
@@ -0,0 +1,26 @@
+require File.dirname(__FILE__) + '/../../spec_helper'
+
+describe TwitterAuth::Dispatcher::Shared do
+  include TwitterAuth::Dispatcher::Shared
+
+  describe '#append_extension_to' do
+    it 'should leave extensions alone if they exist' do
+      append_extension_to('/fake.json').should == '/fake.json'    
+      append_extension_to('/fake.xml').should == '/fake.xml'
+    end
+
+    it 'should append .json if no extension is provided' do
+      append_extension_to('/fake').should == '/fake.json'
+      append_extension_to('/verify/fake').should == '/verify/fake.json'
+    end
+
+    it 'should leave extensions alone even with query strings' do
+      append_extension_to('/fake.json?since_id=123').should == '/fake.json?since_id=123'
+      append_extension_to('/fake.xml?since_id=123').should == '/fake.xml?since_id=123'
+    end
+
+    it 'should add an extension even with query strings' do
+      append_extension_to('/fake?since_id=123').should == '/fake.json?since_id=123'
+    end
+  end
+end