diff --git a/actionpack/lib/sprockets/assets.rake b/actionpack/lib/sprockets/assets.rake
index 6f38ece0c37ca..f1fc7857a747b 100644
--- a/actionpack/lib/sprockets/assets.rake
+++ b/actionpack/lib/sprockets/assets.rake
@@ -23,29 +23,22 @@ namespace :assets do
       manifest = {}
       manifest_path = config.assets.manifest || target
 
-      if env.respond_to?(:each_logical_path)
-        config.assets.precompile.each do |path|
-          env.each_logical_path do |logical_path|
-            if path.is_a?(Regexp)
-              next unless path.match(logical_path)
-            else
-              next unless File.fnmatch(path.to_s, logical_path)
-            end
+      config.assets.precompile.each do |path|
+        env.each_logical_path do |logical_path|
+          if path.is_a?(Regexp)
+            next unless path.match(logical_path)
+          else
+            next unless File.fnmatch(path.to_s, logical_path)
+          end
 
-            if asset = env.find_asset(logical_path)
-              manifest[logical_path] = asset.digest_path
-              filename = target.join(asset.digest_path)
-              mkdir_p filename.dirname
-              asset.write_to(filename)
-              asset.write_to("#{filename}.gz") if filename.to_s =~ /\.(css|js)$/
-            end
+          if asset = env.find_asset(logical_path)
+            manifest[logical_path] = asset.digest_path
+            filename = target.join(asset.digest_path)
+            mkdir_p filename.dirname
+            asset.write_to(filename)
+            asset.write_to("#{filename}.gz") if filename.to_s =~ /\.(css|js)$/
           end
         end
-      else
-        # TODO: Remove this once we're depending on sprockets beta 15
-        assets = config.assets.precompile.dup
-        assets << {:to => target}
-        env.precompile(*assets)
       end
 
       File.open("#{manifest_path}/manifest.yml", 'w') do |f|
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index fa7e3b820b95c..0ca664e4f0561 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -43,7 +43,7 @@ def initialize(*)
         @assets.debug           = false
         @assets.compile         = true
         @assets.digest          = false
-        @assets.manifest        = "#{root}/public#{@assets.prefix}"
+        @assets.manifest        = nil
         @assets.cache_store     = [ :file_store, "#{root}/tmp/cache/assets/" ]
         @assets.js_compressor   = nil
         @assets.css_compressor  = nil
diff --git a/railties/test/application/assets_test.rb b/railties/test/application/assets_test.rb
index ccadf0b2c044d..721d082908851 100644
--- a/railties/test/application/assets_test.rb
+++ b/railties/test/application/assets_test.rb
@@ -96,6 +96,19 @@ def app
       assert_match /application-([0-z]+)\.css/, assets["application.css"]
     end
 
+    test "the manifest file should be saved by default in the same assets folder" do
+      app_file "app/assets/javascripts/application.js", "alert();"
+      app_file "config/initializers/manifest.rb", "Rails.application.config.assets.prefix = '/x'"
+
+      capture(:stdout) do
+        Dir.chdir(app_path){ `bundle exec rake assets:precompile` }
+      end
+
+      manifest = "#{app_path}/public/x/manifest.yml"
+      assets = YAML.load_file(manifest)
+      assert_match /application-([0-z]+)\.js/, assets["application.js"]
+    end
+
     test "assets do not require any assets group gem when manifest file is present" do
       app_file "app/assets/javascripts/application.js", "alert();"