diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index a8abf48441..44790605b2 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *2.3.0 [Edge]*
 
+* Fixed the AssetTagHelper cache to use the computed asset host as part of the cache key instead of just assuming the its a string #1299 [DHH]
+
 * Make ActionController#render(string) work as a shortcut for render :file/:template/:action => string. [#1435] [Pratik Naik] Examples:
 
   # Instead of render(:action => 'other_action')
diff --git a/actionpack/lib/action_view/helpers/asset_tag_helper.rb b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
index 0633d5414e..79b1cdbc48 100644
--- a/actionpack/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
@@ -545,12 +545,12 @@ module ActionView
             @source = source
             @include_host = include_host
             @cache_key = if controller.respond_to?(:request)
-              [self.class.name,controller.request.protocol,
-               ActionController::Base.asset_host,
-               ActionController::Base.relative_url_root,
-               source, include_host]
+              [ self.class.name,controller.request.protocol,
+                compute_asset_host(source),
+                ActionController::Base.relative_url_root,
+                source, include_host ]
             else
-              [self.class.name,ActionController::Base.asset_host, source, include_host]
+              [ self.class.name, compute_asset_host(source), source, include_host ]
             end
           end
           
diff --git a/actionpack/test/template/asset_tag_helper_test.rb b/actionpack/test/template/asset_tag_helper_test.rb
index 7597927f6d..41e7125e01 100644
--- a/actionpack/test/template/asset_tag_helper_test.rb
+++ b/actionpack/test/template/asset_tag_helper_test.rb
@@ -281,6 +281,26 @@ class AssetTagHelperTest < ActionView::TestCase
     assert_equal copy, source
   end
 
+  def test_caching_image_path_with_caching_and_proc_asset_host_using_request
+    ENV['RAILS_ASSET_ID'] = ''
+    ActionController::Base.asset_host = Proc.new do |source, request|
+      if request.ssl?
+        "#{request.protocol}#{request.host_with_port}"
+      else
+        "#{request.protocol}assets#{source.length}.example.com"
+      end
+    end
+    
+    ActionController::Base.perform_caching = true
+
+
+    @controller.request.stubs(:ssl?).returns(false)
+    assert_equal "http://assets15.example.com/images/xml.png", image_path("xml.png")
+
+    @controller.request.stubs(:ssl?).returns(true)
+    assert_equal "http://localhost/images/xml.png", image_path("xml.png")
+  end
+
   def test_caching_javascript_include_tag_when_caching_on
     ENV["RAILS_ASSET_ID"] = ""
     ActionController::Base.asset_host = 'http://a0.example.com'