diff --git a/lib/rack/chunked.rb b/lib/rack/chunked.rb
index 280d89d..dddf969 100644
--- a/lib/rack/chunked.rb
+++ b/lib/rack/chunked.rb
@@ -19,7 +19,7 @@ module Rack
          STATUS_WITH_NO_ENTITY_BODY.include?(status) ||
          headers['Content-Length'] ||
          headers['Transfer-Encoding']
-        [status, headers.to_hash, body]
+        [status, headers, body]
       else
         dup.chunk(status, headers, body)
       end
@@ -29,7 +29,7 @@ module Rack
       @body = body
       headers.delete('Content-Length')
       headers['Transfer-Encoding'] = 'chunked'
-      [status, headers.to_hash, self]
+      [status, headers, self]
     end
 
     def each
diff --git a/lib/rack/content_type.rb b/lib/rack/content_type.rb
index 0c1e1ca..874c28c 100644
--- a/lib/rack/content_type.rb
+++ b/lib/rack/content_type.rb
@@ -17,7 +17,7 @@ module Rack
       status, headers, body = @app.call(env)
       headers = Utils::HeaderHash.new(headers)
       headers['Content-Type'] ||= @content_type
-      [status, headers.to_hash, body]
+      [status, headers, body]
     end
   end
 end
diff --git a/lib/rack/response.rb b/lib/rack/response.rb
index 92c8c4a..a7f9bf2 100644
--- a/lib/rack/response.rb
+++ b/lib/rack/response.rb
@@ -71,9 +71,9 @@ module Rack
 
       if [204, 304].include?(status.to_i)
         header.delete "Content-Type"
-        [status.to_i, header.to_hash, []]
+        [status.to_i, header, []]
       else
-        [status.to_i, header.to_hash, self]
+        [status.to_i, header, self]
       end
     end
     alias to_a finish           # For *response