diff --git a/attentive.gemspec b/attentive.gemspec
index e958bb5..9b24c00 100644
--- a/attentive.gemspec
+++ b/attentive.gemspec
@@ -16,6 +16,7 @@ Gem::Specification.new do |gem|
   gem.version       = Attentive::VERSION
 
   gem.add_dependency 'sinatra'
+  gem.add_dependency 'naturalsort', '~> 1.1.1'
 
   gem.add_dependency 'sprockets'
   gem.add_dependency 'sprockets-vendor_gems'
diff --git a/lib/attentive/server.rb b/lib/attentive/server.rb
index 4fd0609..3c5aa78 100644
--- a/lib/attentive/server.rb
+++ b/lib/attentive/server.rb
@@ -13,6 +13,8 @@ require 'rack/builder'
 
 require 'forwardable'
 
+require 'natural_sort_kernel'
+
 module Attentive
   module Helpers
     def image_path(path, options)
@@ -150,7 +152,7 @@ module Attentive
       def slides
         slides = []
 
-        Dir['presentation/*.slides'].sort.each do |file|
+        Dir['presentation/*.slides'].natural_sort.each do |file|
           File.readlines(file).each do |line|
             if line[%r{^!SLIDE}]
               slides << Slide.new(:classes => line.split(' ')[1..-1])