diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 2fa0aab5df2a5364e4a20d88b255057a7028572c..d480af876dd09209f1342a90ab01acecbc877d21 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -338,7 +338,9 @@ def resources(*resources, &block)
               with_scope_level(:collection) do
                 get "(.:format)", :to => :index, :as => resource.collection_name
                 post "(.:format)", :to => :create
-                get "/new(.:format)", :to => :new, :as => "new_#{resource.singular}"
+                with_exclusive_name_prefix :new do
+                  get "/new(.:format)", :to => :new, :as => resource.singular
+                end
               end
 
               with_scope_level(:member) do
@@ -346,7 +348,9 @@ def resources(*resources, &block)
                   get "(.:format)", :to => :show, :as => resource.member_name
                   put "(.:format)", :to => :update
                   delete "(.:format)", :to => :destroy
-                  get "/edit(.:format)", :to => :edit, :as => "edit_#{resource.singular}"
+                  with_exclusive_name_prefix :edit do
+                    get "/edit(.:format)", :to => :edit, :as => resource.singular
+                  end
                 end
               end
             end
@@ -400,11 +404,8 @@ def match(*args)
           end
 
           if args.first.is_a?(Symbol)
-            begin
-              old_name_prefix, @scope[:name_prefix] = @scope[:name_prefix], "#{args.first}_#{@scope[:name_prefix]}"
+            with_exclusive_name_prefix(args.first) do
               return match("/#{args.first}(.:format)", options.merge(:to => args.first.to_sym))
-            ensure
-              @scope[:name_prefix] = old_name_prefix
             end
           end
 
@@ -430,6 +431,22 @@ def parent_resource
           end
 
         private
+          def with_exclusive_name_prefix(prefix)
+            begin
+              old_name_prefix = @scope[:name_prefix]
+
+              if !old_name_prefix.blank?
+                @scope[:name_prefix] = "#{prefix}_#{@scope[:name_prefix]}"
+              else
+                @scope[:name_prefix] = prefix.to_s
+              end
+
+              yield
+            ensure
+              @scope[:name_prefix] = old_name_prefix
+            end
+          end
+
           def with_scope_level(kind, resource = parent_resource)
             old, @scope[:scope_level] = @scope[:scope_level], kind
             old_resource, @scope[:scope_level_resource] = @scope[:scope_level_resource], resource
diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index 22ef48b668969e00602fb3a0a120b4e33b780313..425796b460cda1eb55e8e96fc9d3c09497882352 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -228,9 +228,23 @@ def test_projects_involvements
       assert_equal 'involvements#index', @response.body
       assert_equal '/projects/1/involvements', project_involvements_path(:project_id => '1')
 
+      get '/projects/1/involvements/new'
+      assert_equal 'involvements#new', @response.body
+      assert_equal '/projects/1/involvements/new', new_project_involvement_path(:project_id => '1')
+
       get '/projects/1/involvements/1'
       assert_equal 'involvements#show', @response.body
       assert_equal '/projects/1/involvements/1', project_involvement_path(:project_id => '1', :id => '1')
+
+      put '/projects/1/involvements/1'
+      assert_equal 'involvements#update', @response.body
+
+      delete '/projects/1/involvements/1'
+      assert_equal 'involvements#destroy', @response.body
+
+      get '/projects/1/involvements/1/edit'
+      assert_equal 'involvements#edit', @response.body
+      assert_equal '/projects/1/involvements/1/edit', edit_project_involvement_path(:project_id => '1', :id => '1')
     end
   end