diff --git a/middleman-core/lib/middleman-core/extensions/automatic_image_sizes.rb b/middleman-core/lib/middleman-core/extensions/automatic_image_sizes.rb
index 86311be7..0f5ef31d 100644
--- a/middleman-core/lib/middleman-core/extensions/automatic_image_sizes.rb
+++ b/middleman-core/lib/middleman-core/extensions/automatic_image_sizes.rb
@@ -4,7 +4,7 @@ class Middleman::Extensions::AutomaticImageSizes < ::Middleman::Extension
     super
 
     # Include 3rd-party fastimage library
-    require 'vendored-middleman-deps/fastimage'
+    require 'fastimage'
   end
 
   helpers do
diff --git a/middleman-core/lib/vendored-middleman-deps/fastimage.rb b/middleman-core/lib/vendored-middleman-deps/fastimage.rb
deleted file mode 100644
index a1d0da26..00000000
--- a/middleman-core/lib/vendored-middleman-deps/fastimage.rb
+++ /dev/null
@@ -1,287 +0,0 @@
-# FastImage finds the size or type of an image given its uri.
-# It is careful to only fetch and parse as much of the image as is needed to determine the result.
-# It does this by using a feature of Net::HTTP that yields strings from the resource being fetched
-# as soon as the packets arrive.
-#
-# No external libraries such as ImageMagick are used here, this is a very lightweight solution to
-# finding image information.
-#
-# FastImage knows about GIF, JPEG, BMP and PNG files.
-#
-# FastImage can also read files from the local filesystem by supplying the path instead of a uri.
-# In this case FastImage uses the open-uri library to read the file in chunks of 256 bytes until
-# it has enough. This is possibly a useful bandwidth-saving feature if the file is on a network
-# attached disk rather than truly local.
-#
-# === Examples
-#   require 'fastimage'
-#
-#   FastImage.size("http://stephensykes.com/images/ss.com_x.gif")
-#   => [266, 56]
-#   FastImage.type("http://stephensykes.com/images/pngimage")
-#   => :png
-#   FastImage.type("/some/local/file.gif")
-#   => :gif
-#
-# === References
-# * http://snippets.dzone.com/posts/show/805
-# * http://www.anttikupila.com/flash/getting-jpg-dimensions-with-as3-without-loading-the-entire-file/
-# * http://pennysmalls.com/2008/08/19/find-jpeg-dimensions-fast-in-ruby/
-# * http://imagesize.rubyforge.org/
-#
-require 'net/https'
-require 'open-uri'
-
-class FastImage
-  attr_reader :size, :type
-
-  class FastImageException < StandardError # :nodoc:
-  end
-  class MoreCharsNeeded < FastImageException # :nodoc:
-  end
-  class UnknownImageType < FastImageException # :nodoc:
-  end
-  class ImageFetchFailure < FastImageException # :nodoc:
-  end
-  class SizeNotFound < FastImageException # :nodoc:
-  end
-
-  DefaultTimeout = 2
-
-  LocalFileChunkSize = 256
-
-  # Returns an array containing the width and height of the image.
-  # It will return nil if the image could not be fetched, or if the image type was not recognised.
-  #
-  # By default there is a timeout of 2 seconds for opening and reading from a remote server.
-  # This can be changed by passing a :timeout => number_of_seconds in the options.
-  #
-  # If you wish FastImage to raise if it cannot size the image for any reason, then pass
-  # :raise_on_failure => true in the options.
-  #
-  # FastImage knows about GIF, JPEG, BMP and PNG files.
-  #
-  # === Example
-  #
-  #   require 'fastimage'
-  #
-  #   FastImage.size("http://stephensykes.com/images/ss.com_x.gif")
-  #   => [266, 56]
-  #   FastImage.size("http://stephensykes.com/images/pngimage")
-  #   => [16, 16]
-  #   FastImage.size("http://farm4.static.flickr.com/3023/3047236863_9dce98b836.jpg")
-  #   => [500, 375]
-  #   FastImage.size("http://www-ece.rice.edu/~wakin/images/lena512.bmp")
-  #   => [512, 512]
-  #   FastImage.size("test/fixtures/test.jpg")
-  #   => [882, 470]
-  #   FastImage.size("http://pennysmalls.com/does_not_exist")
-  #   => nil
-  #   FastImage.size("http://pennysmalls.com/does_not_exist", :raise_on_failure=>true)
-  #   => raises FastImage::ImageFetchFailure
-  #   FastImage.size("http://stephensykes.com/favicon.ico", :raise_on_failure=>true)
-  #   => raises FastImage::UnknownImageType
-  #   FastImage.size("http://stephensykes.com/favicon.ico", :raise_on_failure=>true, :timeout=>0.01)
-  #   => raises FastImage::ImageFetchFailure
-  #   FastImage.size("http://stephensykes.com/images/faulty.jpg", :raise_on_failure=>true)
-  #   => raises FastImage::SizeNotFound
-  #
-  # === Supported options
-  # [:timeout]
-  #   Overrides the default timeout of 2 seconds.  Applies both to reading from and opening the http connection.
-  # [:raise_on_failure]
-  #   If set to true causes an exception to be raised if the image size cannot be found for any reason.
-  #
-  def self.size(uri, options={})
-    new(uri, options).size
-  end
-
-  # Returns an symbol indicating the image type fetched from a uri.
-  # It will return nil if the image could not be fetched, or if the image type was not recognised.
-  #
-  # By default there is a timeout of 2 seconds for opening and reading from a remote server.
-  # This can be changed by passing a :timeout => number_of_seconds in the options.
-  #
-  # If you wish FastImage to raise if it cannot find the type of the image for any reason, then pass
-  # :raise_on_failure => true in the options.
-  #
-  # === Example
-  #
-  #   require 'fastimage'
-  #
-  #   FastImage.type("http://stephensykes.com/images/ss.com_x.gif")
-  #   => :gif
-  #   FastImage.type("http://stephensykes.com/images/pngimage")
-  #   => :png
-  #   FastImage.type("http://farm4.static.flickr.com/3023/3047236863_9dce98b836.jpg")
-  #   => :jpeg
-  #   FastImage.type("http://www-ece.rice.edu/~wakin/images/lena512.bmp")
-  #   => :bmp
-  #   FastImage.type("test/fixtures/test.jpg")
-  #   => :jpeg
-  #   FastImage.type("http://pennysmalls.com/does_not_exist")
-  #   => nil
-  #
-  # === Supported options
-  # [:timeout]
-  #   Overrides the default timeout of 2 seconds.  Applies both to reading from and opening the http connection.
-  # [:raise_on_failure]
-  #   If set to true causes an exception to be raised if the image type cannot be found for any reason.
-  #
-  def self.type(uri, options={})
-    new(uri, options.merge(:type_only=>true)).type
-  end
-
-  def initialize(uri, options={})
-    @property = options[:type_only] ? :type : :size
-    @timeout = options[:timeout] || DefaultTimeout
-    @uri = uri
-    begin
-      @parsed_uri = URI.parse(uri)
-    rescue URI::InvalidURIError
-      fetch_using_open_uri
-    else
-      if @parsed_uri.scheme == "http" || @parsed_uri.scheme == "https"
-        fetch_using_http
-      else
-        fetch_using_open_uri
-      end
-    end
-    raise SizeNotFound if options[:raise_on_failure] && @property == :size && !@size
-  rescue Timeout::Error, SocketError, Errno::ECONNREFUSED, Errno::EHOSTUNREACH, Errno::ECONNRESET,
-    ImageFetchFailure, Net::HTTPBadResponse, EOFError, Errno::ENOENT
-    raise ImageFetchFailure if options[:raise_on_failure]
-  rescue NoMethodError  # 1.8.7p248 can raise this due to a net/http bug
-    raise ImageFetchFailure if options[:raise_on_failure]
-  rescue UnknownImageType
-    raise UnknownImageType if options[:raise_on_failure]
-  end
-
-  private
-
-  def fetch_using_http
-    setup_http
-    @http.request_get(@parsed_uri.request_uri) do |res|
-      raise ImageFetchFailure unless res.is_a?(Net::HTTPSuccess)
-      res.read_body do |str|
-        break if parse_packet(str)
-      end
-    end
-  end
-
-  def setup_http
-    @http = Net::HTTP.new(@parsed_uri.host, @parsed_uri.port)
-    @http.use_ssl = (@parsed_uri.scheme == "https")
-    @http.verify_mode = OpenSSL::SSL::VERIFY_NONE
-    @http.open_timeout = @timeout
-    @http.read_timeout = @timeout
-  end
-
-  def fetch_using_open_uri
-    open(@uri) do |s|
-      while str = s.read(LocalFileChunkSize)
-        break if parse_packet(str)
-      end
-    end
-  end
-
-  # returns true once result is achieved
-  #
-  def parse_packet(str)
-    @str = (@unused_str || "") + str
-    @strpos = 0
-    begin
-      result = send("parse_#{@property}")
-      if result
-        instance_variable_set("@#{@property}", result)
-        true
-      end
-    rescue MoreCharsNeeded
-      false
-    end
-  end
-
-  def parse_size
-    @type = parse_type unless @type
-    @strpos = 0
-    send("parse_size_for_#{@type}")
-  end
-
-  def get_chars(n)
-    if @strpos + n - 1 >= @str.size
-      @unused_str = @str[@strpos..-1]
-      raise MoreCharsNeeded
-    else
-      result = @str[@strpos..(@strpos + n - 1)]
-      @strpos += n
-      result
-    end
-  end
-
-  def get_byte
-    get_chars(1).unpack("C")[0]
-  end
-
-  def read_int(str)
-    size_bytes = str.unpack("CC")
-    (size_bytes[0] << 8) + size_bytes[1]
-  end
-
-  def parse_type
-    case get_chars(2)
-    when "BM"
-      :bmp
-    when "GI"
-      :gif
-    when 0xff.chr + 0xd8.chr
-      :jpeg
-    when 0x89.chr + "P"
-      :png
-    else
-      raise UnknownImageType
-    end
-  end
-
-  def parse_size_for_gif
-    get_chars(11)[6..10].unpack('SS')
-  end
-
-  def parse_size_for_png
-    get_chars(25)[16..24].unpack('NN')
-  end
-
-  def parse_size_for_jpeg
-    loop do
-      @state = case @state
-      when nil
-        get_chars(2)
-        :started
-      when :started
-        get_byte == 0xFF ? :sof : :started
-      when :sof
-        c = get_byte
-        if (0xe0..0xef).include?(c)
-          :skipframe
-        elsif [0xC0..0xC3, 0xC5..0xC7, 0xC9..0xCB, 0xCD..0xCF].detect {|r| r.include? c}
-          :readsize
-        else
-          :skipframe
-        end
-      when :skipframe
-        @skip_chars = read_int(get_chars(2)) - 2
-        :do_skip
-      when :do_skip
-        get_chars(@skip_chars)
-        :started
-      when :readsize
-        s = get_chars(7)
-        return [read_int(s[5..6]), read_int(s[3..4])]
-      end
-    end
-  end
-
-  def parse_size_for_bmp
-    d = get_chars(29)[14..28]
-    d.unpack("C")[0] == 40 ? d[4..-1].unpack('LL') : d[4..8].unpack('SS')
-  end
-end
diff --git a/middleman-core/middleman-core.gemspec b/middleman-core/middleman-core.gemspec
index cdf70080..070339ab 100644
--- a/middleman-core/middleman-core.gemspec
+++ b/middleman-core/middleman-core.gemspec
@@ -34,4 +34,7 @@ Gem::Specification.new do |s|
 
   # i18n
   s.add_dependency('i18n', ['~> 0.6.9'])
+
+  # Automatic Image Sizes
+  s.add_dependency('fastimage', ['~> 1.6.2'])
 end