diff --git a/lib/prerender_rails.rb b/lib/prerender_rails.rb
index ef059c6..3392d02 100644
--- a/lib/prerender_rails.rb
+++ b/lib/prerender_rails.rb
@@ -181,32 +181,21 @@ def get_prerendered_page_response(env)
       end
     end
 
+    def get_cloudflare_scheme(env)
+      match = /"scheme":"(http|https)"/.match(env['CF-VISITOR'])
+      match && match[1]
+    end
 
     def build_api_url(env)
-      new_env = env
-      if env["CF-VISITOR"]
-        match = /"scheme":"(http|https)"/.match(env['CF-VISITOR'])
-        new_env["HTTPS"] = true and new_env["rack.url_scheme"] = "https" and new_env["SERVER_PORT"] = 443 if (match && match[1] == "https")
-        new_env["HTTPS"] = false and new_env["rack.url_scheme"] = "http" and new_env["SERVER_PORT"] = 80 if (match && match[1] == "http")
-      end
-
-      if env["X-FORWARDED-PROTO"]
-        new_env["HTTPS"] = true and new_env["rack.url_scheme"] = "https" and new_env["SERVER_PORT"] = 443 if env["X-FORWARDED-PROTO"].split(',')[0] == "https"
-        new_env["HTTPS"] = false and new_env["rack.url_scheme"] = "http" and new_env["SERVER_PORT"] = 80 if env["X-FORWARDED-PROTO"].split(',')[0] == "http"
-      end
+      request_obj = Rack::Request.new(env)
+      scheme = @options[:protocol] || get_cloudflare_scheme(env) || request_obj.scheme
+      url = "#{scheme}://#{request_obj.host}#{request_obj.fullpath}"
 
-      if @options[:protocol]
-        new_env["HTTPS"] = true and new_env["rack.url_scheme"] = "https" and new_env["SERVER_PORT"] = 443 if @options[:protocol] == "https"
-        new_env["HTTPS"] = false and new_env["rack.url_scheme"] = "http" and new_env["SERVER_PORT"] = 80 if @options[:protocol] == "http"
-      end
-
-      url = Rack::Request.new(new_env).url
       prerender_url = get_prerender_service_url()
       forward_slash = prerender_url[-1, 1] == '/' ? '' : '/'
       "#{prerender_url}#{forward_slash}#{url}"
     end
 
-
     def get_prerender_service_url
       @options[:prerender_service_url] || ENV['PRERENDER_SERVICE_URL'] || 'http://service.prerender.io/'
     end
diff --git a/test/lib/prerender_rails.rb b/test/lib/prerender_rails.rb
index 60d66d9..060f4e2 100644
--- a/test/lib/prerender_rails.rb
+++ b/test/lib/prerender_rails.rb
@@ -200,7 +200,7 @@
 
     # Check X-Forwarded-Proto because Heroku SSL Support terminates at the load balancer
     it "should build the correct api url for the Heroku SSL Addon support with single value" do
-      request = Rack::MockRequest.env_for "http://google.com/search?q=javascript", { 'X-FORWARDED-PROTO' => 'https'}
+      request = Rack::MockRequest.env_for "http://google.com/search?q=javascript", { 'HTTP_X_FORWARDED_PROTO' => 'https'}
       ENV['PRERENDER_SERVICE_URL'] = nil
       assert_equal 'http://service.prerender.io/https://google.com/search?q=javascript', @prerender.build_api_url(request)
     end
@@ -208,7 +208,7 @@
 
     # Check X-Forwarded-Proto because Heroku SSL Support terminates at the load balancer
     it "should build the correct api url for the Heroku SSL Addon support with double value" do
-      request = Rack::MockRequest.env_for "http://google.com/search?q=javascript", { 'X-FORWARDED-PROTO' => 'https,http'}
+      request = Rack::MockRequest.env_for "http://google.com/search?q=javascript", { 'HTTP_X_FORWARDED_PROTO' => 'https,http'}
       ENV['PRERENDER_SERVICE_URL'] = nil
       assert_equal 'http://service.prerender.io/https://google.com/search?q=javascript', @prerender.build_api_url(request)
     end