diff --git a/lib/reel/rack/server.rb b/lib/reel/rack/server.rb
index 96fcd05..1e4e484 100644
--- a/lib/reel/rack/server.rb
+++ b/lib/reel/rack/server.rb
@@ -40,7 +40,9 @@ def route_request(request)
           :input        => request.body.to_s,
           "REMOTE_ADDR" => request.remote_addr
         }.merge(convert_headers(request.headers))
-   
+
+        normalize_env(options)
+
         status, headers, body = app.call ::Rack::MockRequest.env_for(request.url, options)
 
         if body.respond_to? :each
@@ -78,6 +80,26 @@ def convert_headers(headers)
         }]
       end
 
+      # Copied from lib/puma/server.rb
+      def normalize_env(env)
+        if host = env["HTTP_HOST"]
+          if colon = host.index(":")
+            env["SERVER_NAME"] = host[0, colon]
+            env["SERVER_PORT"] = host[colon+1, host.bytesize]
+          else
+            env["SERVER_NAME"] = host
+            env["SERVER_PORT"] = default_server_port(env)
+          end
+        else
+          env["SERVER_NAME"] = "localhost"
+          env["SERVER_PORT"] = default_server_port(env)
+        end
+      end
+
+      def default_server_port(env)
+        env['HTTP_X_FORWARDED_PROTO'] == 'https' ? 443 : 80
+      end
+
       def status_symbol(status)
         if status.is_a?(Fixnum)
           Http::Response::STATUS_CODES[status].downcase.gsub(/\s|-/, '_').to_sym
diff --git a/spec/reel/rack/server_spec.rb b/spec/reel/rack/server_spec.rb
index 8571726..cfdd405 100644
--- a/spec/reel/rack/server_spec.rb
+++ b/spec/reel/rack/server_spec.rb
@@ -10,10 +10,10 @@
   let(:body) { "hello world" }
   let(:uri) { URI("http://#{host}:#{port}/") }
   let(:http) { Net::HTTP.new(uri.host, uri.port) }
+  let(:rack_app) { proc { [200, headers, [body]] } }
 
   subject do
-    app = proc { [200, headers, [body]] }
-    described_class.new(Rack::Lint.new(Rack::Head.new(app)), :Host => host, :Port => port)
+    described_class.new(Rack::Lint.new(Rack::Head.new(rack_app)), :Host => host, :Port => port)
   end
 
   before do
@@ -53,4 +53,20 @@
       expect(http.send_request('GET', uri.path, 'test')['transfer-encoding']).to eq 'chunked'
     end
   end
+
+  context "works with Rack::Builder" do
+    let(:rack_app) {
+      headers = {"Content-Type" => "text/plain"}
+      Rack::Builder.app {
+        map("/path1") { run proc { [200, headers.merge("Content-Length"=>"5"), ["path1"]] } }
+        run proc { [200, headers.merge("Content-Length"=>"3"), ["any"]] }
+      }
+    }
+
+    it "routes the requests both exact path and any path" do
+      expect(http.send_request('GET', "/path1", 'test').body).to eq "path1"
+      expect(http.send_request('GET', "/", 'test').body).to eq "any"
+      expect(http.send_request('GET', "/path2", 'test').body).to eq "any"
+    end
+  end
 end