diff --git a/actionmailer/test/asset_host_test.rb b/actionmailer/test/asset_host_test.rb
new file mode 100644
index 0000000000000..1c92dd266dd5c
--- /dev/null
+++ b/actionmailer/test/asset_host_test.rb
@@ -0,0 +1,54 @@
+require 'abstract_unit'
+
+class AssetHostMailer < ActionMailer::Base
+  def email_with_asset(recipient)
+    recipients recipient
+    subject    "testing email containing asset path while asset_host is set"
+    from       "tester@example.com"
+  end
+end
+
+class AssetHostTest < Test::Unit::TestCase
+  def setup
+    set_delivery_method :test
+    ActionMailer::Base.perform_deliveries = true
+    ActionMailer::Base.deliveries = []
+
+    @recipient = 'test@localhost'
+  end
+
+  def teardown
+    restore_delivery_method
+  end
+
+  def test_asset_host_as_string
+    ActionController::Base.asset_host = "http://www.example.com"
+    mail = AssetHostMailer.deliver_email_with_asset(@recipient)
+    assert_equal "<img alt=\"Somelogo\" src=\"http://www.example.com/images/somelogo.png\" />", mail.body.strip
+  end
+
+  def test_asset_host_as_one_arguement_proc
+    ActionController::Base.asset_host = Proc.new { |source|
+      if source.starts_with?('/images')
+        "http://images.example.com"
+      else
+        "http://assets.example.com"
+      end
+    }
+    mail = AssetHostMailer.deliver_email_with_asset(@recipient)
+    assert_equal "<img alt=\"Somelogo\" src=\"http://images.example.com/images/somelogo.png\" />", mail.body.strip
+  end
+
+  def test_asset_host_as_two_arguement_proc
+    ActionController::Base.asset_host = Proc.new {|source,request|
+      if request && request.ssl?
+        "https://www.example.com"
+      else
+        "http://www.example.com"
+      end
+    }
+    mail = nil
+    assert_nothing_raised { mail = AssetHostMailer.deliver_email_with_asset(@recipient) }
+    assert_equal "<img alt=\"Somelogo\" src=\"http://www.example.com/images/somelogo.png\" />", mail.body.strip
+  end
+end
\ No newline at end of file
diff --git a/actionmailer/test/fixtures/asset_host_mailer/email_with_asset.html.erb b/actionmailer/test/fixtures/asset_host_mailer/email_with_asset.html.erb
new file mode 100644
index 0000000000000..b3f0438d03e78
--- /dev/null
+++ b/actionmailer/test/fixtures/asset_host_mailer/email_with_asset.html.erb
@@ -0,0 +1 @@
+<%= image_tag "somelogo.png" %>
\ No newline at end of file
diff --git a/actionpack/lib/action_view/helpers/asset_tag_helper.rb b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
index 4ec7a383e503a..0633d5414eb00 100644
--- a/actionpack/lib/action_view/helpers/asset_tag_helper.rb
+++ b/actionpack/lib/action_view/helpers/asset_tag_helper.rb
@@ -574,7 +574,7 @@ def mtime
 
           private
             def request
-              @controller.request
+              request? && @controller.request
             end
 
             def request?