diff --git a/.gitignore b/.gitignore
index b62c9a37..81df59a5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,3 +8,4 @@
 /doc
 /.yardoc
 gemfiles/*.lock
+/.idea
diff --git a/lib/api_auth/headers.rb b/lib/api_auth/headers.rb
index 6906ab1f..c87805cd 100644
--- a/lib/api_auth/headers.rb
+++ b/lib/api_auth/headers.rb
@@ -57,7 +57,7 @@ def canonical_string(override_method = nil)
       [request_method.upcase,
        @request.content_type,
        @request.content_md5,
-       parse_uri(@request.request_uri),
+       parse_uri(@request.original_uri || @request.request_uri),
        @request.timestamp].join(',')
     end
 
diff --git a/lib/api_auth/request_drivers/action_controller.rb b/lib/api_auth/request_drivers/action_controller.rb
index 54d0860b..534e3c5b 100644
--- a/lib/api_auth/request_drivers/action_controller.rb
+++ b/lib/api_auth/request_drivers/action_controller.rb
@@ -52,6 +52,10 @@ def content_md5
         value.nil? ? '' : value
       end
 
+      def original_uri
+        find_header(%w(X-ORIGINAL-URI X_ORIGINAL_URI HTTP_X_ORIGINAL_URI))
+      end
+
       def request_uri
         @request.request_uri
       end
diff --git a/lib/api_auth/request_drivers/curb.rb b/lib/api_auth/request_drivers/curb.rb
index 8509b43f..83e2cea2 100644
--- a/lib/api_auth/request_drivers/curb.rb
+++ b/lib/api_auth/request_drivers/curb.rb
@@ -41,6 +41,10 @@ def content_md5
         value.nil? ? '' : value
       end
 
+      def original_uri
+        find_header(%w(X-ORIGINAL-URI X_ORIGINAL_URI HTTP_X_ORIGINAL_URI))
+      end
+
       def request_uri
         @request.url
       end
diff --git a/lib/api_auth/request_drivers/faraday.rb b/lib/api_auth/request_drivers/faraday.rb
index a213bef7..f76fb5f2 100644
--- a/lib/api_auth/request_drivers/faraday.rb
+++ b/lib/api_auth/request_drivers/faraday.rb
@@ -52,6 +52,10 @@ def content_md5
         value.nil? ? '' : value
       end
 
+      def original_uri
+        find_header(%w(X-ORIGINAL-URI X_ORIGINAL_URI HTTP_X_ORIGINAL_URI))
+      end
+
       def request_uri
         query_string = @request.params.to_query
         query_string = nil if query_string.empty?
diff --git a/lib/api_auth/request_drivers/httpi.rb b/lib/api_auth/request_drivers/httpi.rb
index c158c72d..ef7fd9c2 100644
--- a/lib/api_auth/request_drivers/httpi.rb
+++ b/lib/api_auth/request_drivers/httpi.rb
@@ -51,6 +51,10 @@ def content_md5
         value.nil? ? '' : value
       end
 
+      def original_uri
+        find_header(%w(X-ORIGINAL-URI X_ORIGINAL_URI HTTP_X_ORIGINAL_URI))
+      end
+
       def request_uri
         @request.url.request_uri
       end
diff --git a/lib/api_auth/request_drivers/net_http.rb b/lib/api_auth/request_drivers/net_http.rb
index 55d33e1f..d213a872 100644
--- a/lib/api_auth/request_drivers/net_http.rb
+++ b/lib/api_auth/request_drivers/net_http.rb
@@ -58,6 +58,10 @@ def content_md5
         value.nil? ? '' : value
       end
 
+      def original_uri
+        find_header(%w(X-ORIGINAL-URI X_ORIGINAL_URI HTTP_X_ORIGINAL_URI))
+      end
+
       def request_uri
         @request.path
       end
diff --git a/lib/api_auth/request_drivers/rack.rb b/lib/api_auth/request_drivers/rack.rb
index 80bd5d53..ae17a845 100644
--- a/lib/api_auth/request_drivers/rack.rb
+++ b/lib/api_auth/request_drivers/rack.rb
@@ -57,6 +57,10 @@ def content_md5
         value.nil? ? '' : value
       end
 
+      def original_uri
+        find_header(%w(X-ORIGINAL-URI X_ORIGINAL_URI HTTP_X_ORIGINAL_URI))
+      end
+
       def request_uri
         @request.fullpath
       end
diff --git a/lib/api_auth/request_drivers/rest_client.rb b/lib/api_auth/request_drivers/rest_client.rb
index a76ad485..e2a5d274 100644
--- a/lib/api_auth/request_drivers/rest_client.rb
+++ b/lib/api_auth/request_drivers/rest_client.rb
@@ -60,6 +60,10 @@ def content_md5
         value.nil? ? '' : value
       end
 
+      def original_uri
+        find_header(%w(X-ORIGINAL-URI X_ORIGINAL_URI HTTP_X_ORIGINAL_URI))
+      end
+
       def request_uri
         @request.url
       end
diff --git a/spec/headers_spec.rb b/spec/headers_spec.rb
index ecb96302..4b2946fd 100644
--- a/spec/headers_spec.rb
+++ b/spec/headers_spec.rb
@@ -96,6 +96,31 @@
           end
         end
       end
+
+      context "when there's a proxy server (e.g. Nginx) with rewrite rules" do
+        let(:request) do
+          Faraday::Request.create('GET') do |req|
+            req.options = Faraday::RequestOptions.new(Faraday::FlatParamsEncoder)
+            req.params = Faraday::Utils::ParamsHash.new
+            req.url('/resource.xml?foo=bar&bar=foo')
+            req.headers = { 'X-Original-URI' => '/api/resource.xml?foo=bar&bar=foo' }
+          end
+        end
+        subject(:headers) { described_class.new(request) }
+        let(:driver) { headers.instance_variable_get('@request') }
+
+        before do
+          allow(driver).to receive(:content_type).and_return 'text/html'
+          allow(driver).to receive(:content_md5).and_return '12345'
+          allow(driver).to receive(:timestamp).and_return 'Mon, 23 Jan 1984 03:29:56 GMT'
+        end
+
+        context 'the driver uses the original_uri' do
+          it 'constructs the canonical_string with the original_uri' do
+            expect(headers.canonical_string).to eq 'GET,text/html,12345,/api/resource.xml?foo=bar&bar=foo,Mon, 23 Jan 1984 03:29:56 GMT'
+          end
+        end
+      end
     end
   end