diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 42b8d8f05f932..ff8d6092a1065 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,5 +1,26 @@
 ## unreleased ##
 
+*   Use a case insensitive URI Regexp for #asset_path.
+
+    This fix a problem where the same asset path using different case are generating
+    different URIs.
+
+    Before:
+
+        image_tag("HTTP://google.com")
+        # => "<img alt=\"Google\" src=\"/assets/HTTP://google.com\" />"
+        image_tag("http://google.com")
+        # => "<img alt=\"Google\" src=\"http://google.com\" />"
+
+    After:
+
+        image_tag("HTTP://google.com")
+        # => "<img alt=\"Google\" src=\"HTTP://google.com\" />"
+        image_tag("http://google.com")
+        # => "<img alt=\"Google\" src=\"http://google.com\" />"
+
+    *David Celis*
+
 *   Add `has_named_route?(route_name)` to the mapper API.
 
     *José Valim*
diff --git a/actionpack/lib/action_view/helpers/asset_url_helper.rb b/actionpack/lib/action_view/helpers/asset_url_helper.rb
index b5f2df76abd1e..0b957adb91174 100644
--- a/actionpack/lib/action_view/helpers/asset_url_helper.rb
+++ b/actionpack/lib/action_view/helpers/asset_url_helper.rb
@@ -105,7 +105,7 @@ module Helpers
     #   )
     #
     module AssetUrlHelper
-      URI_REGEXP = %r{^[-a-z]+://|^(?:cid|data):|^//}
+      URI_REGEXP = %r{^[-a-z]+://|^(?:cid|data):|^//}i
 
       # Computes the path to asset in public directory. If :type
       # options is set, a file extension will be appended and scoped
diff --git a/actionpack/test/template/asset_tag_helper_test.rb b/actionpack/test/template/asset_tag_helper_test.rb
index 67f593c22fad2..2bf96cbe849e8 100644
--- a/actionpack/test/template/asset_tag_helper_test.rb
+++ b/actionpack/test/template/asset_tag_helper_test.rb
@@ -48,6 +48,9 @@ def url_for(*args)
     %(asset_path("style.min"))        => %(/style.min),
     %(asset_path("style.min.css"))    => %(/style.min.css),
 
+    %(asset_path("http://www.outside.com/image.jpg")) => %(http://www.outside.com/image.jpg),
+    %(asset_path("HTTP://www.outside.com/image.jpg")) => %(HTTP://www.outside.com/image.jpg),
+
     %(asset_path("style", type: :stylesheet)) => %(/stylesheets/style.css),
     %(asset_path("xmlhr", type: :javascript)) => %(/javascripts/xmlhr.js),
     %(asset_path("xml.png", type: :image))    => %(/images/xml.png)
@@ -443,8 +446,8 @@ def test_image_alt
     [nil, '/', '/foo/bar/', 'foo/bar/'].each do |prefix|
       assert_equal 'Rails', image_alt("#{prefix}rails.png")
       assert_equal 'Rails', image_alt("#{prefix}rails-9c0a079bdd7701d7e729bd956823d153.png")
-      assert_equal 'Long file name with hyphens', image_alt("#{prefix}long-file-name-with-hyphens.png") 
-      assert_equal 'Long file name with underscores', image_alt("#{prefix}long_file_name_with_underscores.png")  
+      assert_equal 'Long file name with hyphens', image_alt("#{prefix}long-file-name-with-hyphens.png")
+      assert_equal 'Long file name with underscores', image_alt("#{prefix}long_file_name_with_underscores.png")
     end
   end