diff --git a/Gemfile b/Gemfile
index 5b4d46d6..5b6a046f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,9 +1,24 @@
-source 'https://rubygems.org'
+source "https://rubygems.org"
 
 # Specify your gem's dependencies in html-pipeline.gemspec
 gemspec
 
 group :development do
-  gem 'bundler'
-  gem 'rake'
+  gem "bundler"
+  gem "rake"
+end
+
+group :test do
+  gem "rinku",            "~> 1.7",   :require => false
+  gem "gemoji",           "~> 1.0",   :require => false
+  gem "RedCloth",         "~> 4.2.9", :require => false
+  gem "escape_utils",     "~> 0.3",   :require => false
+  gem "github-linguist",  "~> 2.6.2", :require => false
+  gem "github-markdown",  "~> 0.5",   :require => false
+
+  if RUBY_VERSION < "1.9.2"
+    gem "sanitize", ">= 2", "< 2.0.4", :require => false
+  else
+    gem "sanitize", "~> 2.0",          :require => false
+  end
 end
diff --git a/README.md b/README.md
index 7b15b9a0..20562b75 100644
--- a/README.md
+++ b/README.md
@@ -98,6 +98,29 @@ filter.call
 * `TextileFilter` - convert textile to html
 * `TableOfContentsFilter` - anchor headings with name attributes and generate Table of Contents html unordered list linking headings
 
+## Dependencies
+
+Filter gem dependencies are not bundled; you must bundle the filter's gem
+dependencies. The below list details filters with dependencies. For example,
+`SyntaxHighlightFilter` uses [github-linguist](https://github.com/github/linguist)
+to detect and highlight languages. For example, to use the `SyntaxHighlightFilter`,
+add the following to your Gemfile:
+
+```ruby
+gem 'github-linguist'
+```
+
+* `AutolinkFilter` - `rinku`
+* `EmailReplyFilter` - `escape_utils`
+* `EmojiFilter` - `gemoji`
+* `MarkdownFilter` - `github-markdown`
+* `PlainTextInputFilter` - `escape_utils`
+* `SanitizationFilter` - `sanitize`
+* `SyntaxHighlightFilter` - `github-linguist`
+* `TextileFilter` - `RedCloth`
+
+_Note:_ See [Gemfile](/Gemfile) `:test` block for version requirements.
+
 ## 3rd Party Extensions
 
 If you have an idea for a filter, propose it as
@@ -107,19 +130,6 @@ built as an external gem.
 
 * [html-pipeline-asciidoc_filter](https://github.com/asciidoctor/html-pipeline-asciidoc_filter) - asciidoc support
 
-
-## Syntax highlighting
-
-`SyntaxHighlightFilter` uses [github-linguist](https://github.com/github/linguist)
-to detect and highlight languages. It isn't included as a dependency by default
-because it's a large dependency and
-[a hassle to build on heroku](https://github.com/jch/html-pipeline/issues/33).
-To use the filter, add the following to your Gemfile:
-
-```ruby
-gem 'github-linguist'
-```
-
 ## Examples
 
 We define different pipelines for different parts of our app. Here are a few
diff --git a/bin/html-pipeline b/bin/html-pipeline
index eb4064ca..f1d8ed45 100755
--- a/bin/html-pipeline
+++ b/bin/html-pipeline
@@ -54,8 +54,6 @@ else
     case name
     when "Text"
       raise NameError # Text filter doesn't work, no call method
-    when "Textile"
-      require "RedCloth" # Textile filter doesn't require RedCloth
     end
 
     HTML::Pipeline.const_get("#{name}Filter")
@@ -77,4 +75,4 @@ context = {
   :gfm        => true
 }
 
-puts HTML::Pipeline.new(filters, context).call(ARGF.read)[:output]
\ No newline at end of file
+puts HTML::Pipeline.new(filters, context).call(ARGF.read)[:output]
diff --git a/html-pipeline.gemspec b/html-pipeline.gemspec
index 154d209c..9737aa6f 100644
--- a/html-pipeline.gemspec
+++ b/html-pipeline.gemspec
@@ -15,13 +15,15 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^test})
   gem.require_paths = ["lib"]
 
-  gem.add_dependency "gemoji",          "~> 1.0"
-  gem.add_dependency "nokogiri",        RUBY_VERSION < "1.9.2" ? [">= 1.4", "< 1.6"] : "~> 1.4"
-  gem.add_dependency "github-markdown", "~> 0.5"
-  gem.add_dependency "sanitize",        RUBY_VERSION < "1.9.2" ? [">= 2", "< 2.0.4"] : "~> 2.0"
-  gem.add_dependency "rinku",           "~> 1.7"
-  gem.add_dependency "escape_utils",    "~> 0.3"
-  gem.add_dependency "activesupport",   RUBY_VERSION < "1.9.3" ? [">= 2", "< 4"] : ">= 2"
+  gem.add_dependency "nokogiri",      RUBY_VERSION < "1.9.2" ? [">= 1.4", "< 1.6"] : "~> 1.4"
+  gem.add_dependency "activesupport", RUBY_VERSION < "1.9.3" ? [">= 2", "< 4"] : ">= 2"
 
-  gem.add_development_dependency "github-linguist", "~> 2.6.2"
+  gem.post_install_message = <<msg
+-------------------------------------------------
+Thank you for installing html-pipeline!
+You must bundle Filter gem dependencies.
+See html-pipeline README.md for more details.
+https://github.com/jch/html-pipeline#dependencies
+-------------------------------------------------
+msg
 end
diff --git a/lib/html/pipeline.rb b/lib/html/pipeline.rb
index eb24cb3a..2e526d93 100644
--- a/lib/html/pipeline.rb
+++ b/lib/html/pipeline.rb
@@ -1,6 +1,5 @@
 require "nokogiri"
 require "active_support/xml_mini/nokogiri" # convert Documents to hashes
-require "escape_utils"
 
 module HTML
   # GitHub HTML processing filters and utilities. This module includes a small
diff --git a/lib/html/pipeline/autolink_filter.rb b/lib/html/pipeline/autolink_filter.rb
index 6076898f..4a2f6f73 100644
--- a/lib/html/pipeline/autolink_filter.rb
+++ b/lib/html/pipeline/autolink_filter.rb
@@ -1,4 +1,8 @@
-require 'rinku'
+begin
+  require "rinku"
+rescue LoadError => _
+  abort "Missing dependency 'rinku' for AutolinkFilter. See README.md for details."
+end
 
 module HTML
   class Pipeline
diff --git a/lib/html/pipeline/email_reply_filter.rb b/lib/html/pipeline/email_reply_filter.rb
index a63a09a2..cb8261a8 100644
--- a/lib/html/pipeline/email_reply_filter.rb
+++ b/lib/html/pipeline/email_reply_filter.rb
@@ -1,3 +1,9 @@
+begin
+  require "escape_utils"
+rescue LoadError => _
+  abort "Missing dependency 'escape_utils' for EmailReplyFilter. See README.md for details."
+end
+
 module HTML
   class Pipeline
     # HTML Filter that converts email reply text into an HTML DocumentFragment.
@@ -53,4 +59,4 @@ def call
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/emoji_filter.rb b/lib/html/pipeline/emoji_filter.rb
index 87fb8828..b061cf5d 100644
--- a/lib/html/pipeline/emoji_filter.rb
+++ b/lib/html/pipeline/emoji_filter.rb
@@ -1,4 +1,8 @@
-require 'emoji'
+begin
+  require "gemoji"
+rescue LoadError => _
+  abort "Missing dependency 'gemoji' for EmojiFilter. See README.md for details."
+end
 
 module HTML
   class Pipeline
@@ -51,4 +55,4 @@ def asset_root
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/markdown_filter.rb b/lib/html/pipeline/markdown_filter.rb
index 6c25494e..d08e5412 100644
--- a/lib/html/pipeline/markdown_filter.rb
+++ b/lib/html/pipeline/markdown_filter.rb
@@ -1,4 +1,8 @@
-require 'github/markdown'
+begin
+  require "github/markdown"
+rescue LoadError => _
+  abort "Missing dependency 'github-markdown' for MarkdownFilter. See README.md for details."
+end
 
 module HTML
   class Pipeline
@@ -26,4 +30,4 @@ def call
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/plain_text_input_filter.rb b/lib/html/pipeline/plain_text_input_filter.rb
index 3e776a75..c6e468d7 100644
--- a/lib/html/pipeline/plain_text_input_filter.rb
+++ b/lib/html/pipeline/plain_text_input_filter.rb
@@ -1,3 +1,9 @@
+begin
+  require "escape_utils"
+rescue LoadError => _
+  abort "Missing dependency 'escape_utils' for PlainTextInputFilter. See README.md for details."
+end
+
 module HTML
   class Pipeline
     # Simple filter for plain text input. HTML escapes the text input and wraps it
@@ -8,4 +14,4 @@ def call
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/sanitization_filter.rb b/lib/html/pipeline/sanitization_filter.rb
index b5d65cf7..33877bc6 100644
--- a/lib/html/pipeline/sanitization_filter.rb
+++ b/lib/html/pipeline/sanitization_filter.rb
@@ -1,4 +1,8 @@
-require 'sanitize'
+begin
+  require "sanitize"
+rescue LoadError => _
+  abort "Missing dependency 'sanitize' for SanitizationFilter. See README.md for details."
+end
 
 module HTML
   class Pipeline
diff --git a/lib/html/pipeline/syntax_highlight_filter.rb b/lib/html/pipeline/syntax_highlight_filter.rb
index c3c4e6ea..ccdd31e0 100644
--- a/lib/html/pipeline/syntax_highlight_filter.rb
+++ b/lib/html/pipeline/syntax_highlight_filter.rb
@@ -1,7 +1,7 @@
 begin
-  require 'linguist'
-rescue LoadError
-  raise LoadError, "You need to install 'github-linguist' before using the SyntaxHighlightFilter. See README.md for details"
+  require "linguist"
+rescue LoadError => _
+  abort "Missing dependency 'github-linguist' for SyntaxHighlightFilter. See README.md for details."
 end
 
 module HTML
diff --git a/lib/html/pipeline/textile_filter.rb b/lib/html/pipeline/textile_filter.rb
index 31619087..d08bce33 100644
--- a/lib/html/pipeline/textile_filter.rb
+++ b/lib/html/pipeline/textile_filter.rb
@@ -1,3 +1,9 @@
+begin
+  require "redcloth"
+rescue LoadError => _
+  abort "Missing dependency 'RedCloth' for TextileFilter. See README.md for details."
+end
+
 module HTML
   class Pipeline
     # HTML Filter that converts Textile text into HTML and converts into a
@@ -18,4 +24,4 @@ def call
       end
     end
   end
-end
\ No newline at end of file
+end