Use `Utils::HeaderHash` to add to existing headers. Fixes #1222.

2 files changed, 9 insertions, 1 deletions

diff --git a/lib/rack/runtime.rb b/lib/rack/runtime.rb
index a0f8ac7f..d9b2d8ed 100644
--- a/lib/rack/runtime.rb
+++ b/lib/rack/runtime.rb
@@ -20,9 +20,11 @@ module Rack
     def call(env)
       start_time = Utils.clock_time
       status, headers, body = @app.call(env)
+      headers = Utils::HeaderHash[headers]
+
       request_time = Utils.clock_time - start_time
 
-      unless headers.has_key?(@header_name)
+      unless headers.key?(@header_name)
         headers[@header_name] = FORMAT_STRING % request_time
       end
 
diff --git a/test/spec_runtime.rb b/test/spec_runtime.rb
index 10c0c382..e4fc3f95 100644
--- a/test/spec_runtime.rb
+++ b/test/spec_runtime.rb
@@ -11,6 +11,12 @@ describe Rack::Runtime do
     Rack::MockRequest.env_for
   end
 
+  it "works even if headers is an array" do
+    app = lambda { |env| [200, [['Content-Type', 'text/plain']], "Hello, World!"] }
+    response = runtime_app(app).call(request)
+    response[1]['X-Runtime'].must_match(/[\d\.]+/)
+  end
+
   it "sets X-Runtime is none is set" do
     app = lambda { |env| [200, { 'Content-Type' => 'text/plain' }, "Hello, World!"] }
     response = runtime_app(app).call(request)