diff --git a/doc-src/HAML_CHANGELOG.md b/doc-src/HAML_CHANGELOG.md
index 487f9cc9..40e6d504 100644
--- a/doc-src/HAML_CHANGELOG.md
+++ b/doc-src/HAML_CHANGELOG.md
@@ -8,6 +8,9 @@
 * The `form_tag` Rails helper is now properly marked as HTML-safe
   when using Rails' XSS protection with Rails 2.3.5.
 
+* Calls to `defined?` shouldn't interfere with Rails' autoloading
+  in very old versions (1.2.x).
+
 ## 2.2.19
 
 [Tagged on GitHub](http://github.com/nex3/haml/commit/2.2.19).
diff --git a/doc-src/SASS_CHANGELOG.md b/doc-src/SASS_CHANGELOG.md
index 11b0d339..486282f6 100644
--- a/doc-src/SASS_CHANGELOG.md
+++ b/doc-src/SASS_CHANGELOG.md
@@ -11,6 +11,9 @@
   rather than letting the exception bubble up.
   This is consistent with other sorts of sassc corruption handling.
 
+* Calls to `defined?` shouldn't interfere with Rails' autoloading
+  in very old versions (1.2.x).
+
 ## 2.2.19
 
 [Tagged on GitHub](http://github.com/nex3/haml/commit/2.2.18).
diff --git a/lib/haml/helpers/action_view_mods.rb b/lib/haml/helpers/action_view_mods.rb
index a05373ff..1ff50094 100644
--- a/lib/haml/helpers/action_view_mods.rb
+++ b/lib/haml/helpers/action_view_mods.rb
@@ -125,7 +125,7 @@ module ActionView
         @template_object.send :is_haml?
       end
 
-      unless defined?(ActionView::Helpers::ActiveRecordInstanceTag)
+      unless defined?(ActionView::Helpers) && defined?(ActionView::Helpers::ActiveRecordInstanceTag)
         alias_method :content_tag_without_haml, :content_tag
         alias_method :content_tag, :content_tag_with_haml
       end
diff --git a/lib/haml/template.rb b/lib/haml/template.rb
index b738c320..8af68720 100644
--- a/lib/haml/template.rb
+++ b/lib/haml/template.rb
@@ -46,7 +46,8 @@ end
 # Decide how we want to load Haml into Rails.
 # Patching was necessary for versions <= 2.0.1,
 # but we can make it a normal handler for higher versions.
-if defined?(ActionView::TemplateHandler) || defined?(ActionView::Template::Handler)
+if defined?(ActionView::TemplateHandler) ||
+    (defined?(ActionView::Template) && defined?(ActionView::Template::Handler))
   require 'haml/template/plugin'
 else
   require 'haml/template/patch'
diff --git a/lib/haml/template/plugin.rb b/lib/haml/template/plugin.rb
index a270a38c..0a8ce842 100644
--- a/lib/haml/template/plugin.rb
+++ b/lib/haml/template/plugin.rb
@@ -3,8 +3,11 @@
 
 module Haml
   class Plugin < Haml::Util.av_template_class(:Handler)
-    if defined?(ActionView::TemplateHandlers::Compilable) ||
-        defined?(ActionView::Template::Handlers::Compilable)
+    if (defined?(ActionView::TemplateHandlers) &&
+        defined?(ActionView::TemplateHandlers::Compilable)) ||
+       (defined?(ActionView::Template) &&
+        defined?(ActionView::Template::Handlers) &&
+        defined?(ActionView::Template::Handlers::Compilable))
       include Haml::Util.av_template_class(:Handlers)::Compilable
     end
 
diff --git a/lib/sass/plugin/rack.rb b/lib/sass/plugin/rack.rb
index 9275b4ba..b61721e3 100644
--- a/lib/sass/plugin/rack.rb
+++ b/lib/sass/plugin/rack.rb
@@ -48,12 +48,12 @@ module Sass
       # This is automatically done once the Rack plugin is activated.
       # This is done so that the stylesheets aren't checked twice for each request.
       def self.disable_native_plugin!
-        if defined?(Merb::Rack::Application) &&
+        if defined?(Merb::Rack) && defined?(Merb::Rack::Application) &&
             Haml::Util.has?(:instance_method, Merb::Rack::Application, :call_without_sass)
           Merb::Rack::Application.instance_eval {alias_method :call, :call_without_sass}
         end
 
-        if defined?(ActionDispatch::Callbacks.to_prepare)
+        if defined?(ActionDispatch::Callbacks) && defined?(ActionDispatch::Callbacks.to_prepare)
           ActionDispatch::Callbacks.skip_callback(:prepare, :__sass_process)
         elsif defined?(ActionController::Base) &&
             Haml::Util.has?(:instance_method, ActionController::Base, :sass_old_process)
diff --git a/lib/sass/plugin/rails.rb b/lib/sass/plugin/rails.rb
index 0d2c6292..07412677 100644
--- a/lib/sass/plugin/rails.rb
+++ b/lib/sass/plugin/rails.rb
@@ -7,7 +7,8 @@ unless defined?(Sass::RAILS_LOADED)
                               :always_check      => Haml::Util.rails_env != "production",
                               :full_exception    => Haml::Util.rails_env != "production")
 
-  if defined?(ActionDispatch::Callbacks.to_prepare)
+  if defined?(ActionDispatch::Callbacks) &&
+      defined?(ActionDispatch::Callbacks.to_prepare)
     # Rails >= 3.0.0
     ActionDispatch::Callbacks.to_prepare(:sass_process) {Sass::Plugin.check_for_updates}
   else