diff --git a/lib/prawn-rails/config.rb b/lib/prawn-rails/config.rb
index 3f8b2fa..70e8cca 100644
--- a/lib/prawn-rails/config.rb
+++ b/lib/prawn-rails/config.rb
@@ -1,12 +1,27 @@
-require 'ostruct'
-
 module PrawnRails
-  extend self
+  class Config < HashWithIndifferentAccess
+    def method_missing(method_name, *args)
+      # to replace behaviour of previous openstruct-based configuration object
+
+      method_name = method_name.to_s
 
-  @config = OpenStruct.new(page_layout: :portrait, page_size: "A4", skip_page_creation: false)
+      if method_name.end_with?("=")
+        key = method_name.sub(/=$/, "")
+        self[key] = args.first
+      else
+        self[method_name]
+      end
+    end
+  end
+
+  @config = Config.new.merge(
+    page_layout: :portrait,
+    page_size: "A4",
+    skip_page_creation: false,
+  )
 
   def config(&block)
     block_given? ? yield(@config) : @config
   end
-
+  module_function :config
 end
diff --git a/lib/prawn-rails/document.rb b/lib/prawn-rails/document.rb
index 133cee7..37bfde3 100644
--- a/lib/prawn-rails/document.rb
+++ b/lib/prawn-rails/document.rb
@@ -4,7 +4,7 @@
 module PrawnRails
   class Document < Prawn::Document
     def initialize(options = {})
-      options = PrawnRails.config.marshal_dump.merge(options) ### For Ruby 1.9.3 support, use `marshal_dump` instead of `to_h`
+      options = PrawnRails.config.merge(options)
 
       super(options)
     end
diff --git a/test/unit/config_test.rb b/test/unit/config_test.rb
index 87f9c30..00f01fb 100644
--- a/test/unit/config_test.rb
+++ b/test/unit/config_test.rb
@@ -19,7 +19,7 @@ def teardown
   end
 
   test "has a default config" do
-    assert_equal PrawnRails.config.to_h, {page_layout: :portrait, page_size: "A4", skip_page_creation: false}
+    assert_equal PrawnRails.config.to_h.symbolize_keys, {page_layout: :portrait, page_size: "A4", skip_page_creation: false}
   end
 
   test "config can be set with block syntax" do
@@ -28,7 +28,7 @@ def teardown
       config.page_size = "A8"
     end
 
-    assert_equal PrawnRails.config.to_h, {page_layout: :landscape, page_size: "A8", skip_page_creation: false}
+    assert_equal PrawnRails.config.to_h.symbolize_keys, {page_layout: :landscape, page_size: "A8", skip_page_creation: false}
   end
 
 end