diff --git a/src/Orchard.Web/Modules/Orchard.Users/Orchard.Users.csproj b/src/Orchard.Web/Modules/Orchard.Users/Orchard.Users.csproj
index 7c093b830..fd831ffa6 100644
--- a/src/Orchard.Web/Modules/Orchard.Users/Orchard.Users.csproj
+++ b/src/Orchard.Web/Modules/Orchard.Users/Orchard.Users.csproj
@@ -44,8 +44,8 @@
     <Reference Include="System.ComponentModel.DataAnnotations">
       <RequiredTargetFramework>3.5</RequiredTargetFramework>
     </Reference>
-    <Reference Include="System.Web.ApplicationServices" />
     <Reference Include="System.Web" />
+    <Reference Include="System.Web.ApplicationServices, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />
     <Reference Include="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\..\..\lib\aspnetmvc\System.Web.Mvc.dll</HintPath>