diff --git a/lib/nhibernate/PATCH.txt b/lib/nhibernate/PATCH.txt
index ed2fb068e..aa8dcdeaf 100644
--- a/lib/nhibernate/PATCH.txt
+++ b/lib/nhibernate/PATCH.txt
@@ -1 +1,14 @@
-This is a patched version of NHibernate to prevent background JIT from failing.
\ No newline at end of file
+This is a patched version of NHibernate to prevent background JIT from failing.
+Applied https://nhibernate.jira.com/browse/NH-2958:
+
+        private static XmlSerializer _mappingDocumentSerializer = null; 
+
+        private XmlSerializer mappingDocumentSerializer 
+        { 
+            get 
+            { 
+                if (_mappingDocumentSerializer == null) 
+                    _mappingDocumentSerializer = new XmlSerializer(typeof (HbmMapping)); 
+                return _mappingDocumentSerializer; 
+            } 
+        } 
\ No newline at end of file
diff --git a/src/Orchard.Core.Tests/Orchard.Core.Tests.csproj b/src/Orchard.Core.Tests/Orchard.Core.Tests.csproj
index dc1c81a42..3e0a67193 100644
--- a/src/Orchard.Core.Tests/Orchard.Core.Tests.csproj
+++ b/src/Orchard.Core.Tests/Orchard.Core.Tests.csproj
@@ -74,7 +74,7 @@
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\lib\moq\Moq.dll</HintPath>
     </Reference>
-    <Reference Include="NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
+    <Reference Include="NHibernate, Version=3.3.1.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\lib\nhibernate\NHibernate.dll</HintPath>
     </Reference>
diff --git a/src/Orchard.Specs/Orchard.Specs.csproj b/src/Orchard.Specs/Orchard.Specs.csproj
index 44463b67b..81e33394e 100644
--- a/src/Orchard.Specs/Orchard.Specs.csproj
+++ b/src/Orchard.Specs/Orchard.Specs.csproj
@@ -82,7 +82,7 @@
     <Reference Include="log4net">
       <HintPath>..\..\lib\log4net\log4net.dll</HintPath>
     </Reference>
-    <Reference Include="NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
+    <Reference Include="NHibernate, Version=3.3.1.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\lib\nhibernate\NHibernate.dll</HintPath>
     </Reference>
diff --git a/src/Orchard.Tests.Modules/Orchard.Tests.Modules.csproj b/src/Orchard.Tests.Modules/Orchard.Tests.Modules.csproj
index 6dbf81e48..7048e937b 100644
--- a/src/Orchard.Tests.Modules/Orchard.Tests.Modules.csproj
+++ b/src/Orchard.Tests.Modules/Orchard.Tests.Modules.csproj
@@ -99,7 +99,7 @@
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\lib\moq\Moq.dll</HintPath>
     </Reference>
-    <Reference Include="NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
+    <Reference Include="NHibernate, Version=3.3.1.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\lib\nhibernate\NHibernate.dll</HintPath>
     </Reference>
diff --git a/src/Orchard.Tests/Orchard.Framework.Tests.csproj b/src/Orchard.Tests/Orchard.Framework.Tests.csproj
index a3121bb14..738eb2179 100644
--- a/src/Orchard.Tests/Orchard.Framework.Tests.csproj
+++ b/src/Orchard.Tests/Orchard.Framework.Tests.csproj
@@ -109,7 +109,7 @@
     <Reference Include="Newtonsoft.Json">
       <HintPath>..\..\lib\newtonsoft.json\Newtonsoft.Json.dll</HintPath>
     </Reference>
-    <Reference Include="NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
+    <Reference Include="NHibernate, Version=3.3.1.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\lib\nhibernate\NHibernate.dll</HintPath>
     </Reference>
diff --git a/src/Orchard.Web/Modules/Orchard.Projections/Tests/Orchard.Projections.Tests.csproj b/src/Orchard.Web/Modules/Orchard.Projections/Tests/Orchard.Projections.Tests.csproj
index d75c894a3..6acee7922 100644
--- a/src/Orchard.Web/Modules/Orchard.Projections/Tests/Orchard.Projections.Tests.csproj
+++ b/src/Orchard.Web/Modules/Orchard.Projections/Tests/Orchard.Projections.Tests.csproj
@@ -42,7 +42,7 @@
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\..\..\..\lib\nhibernate\Iesi.Collections.dll</HintPath>
     </Reference>
-    <Reference Include="NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
+    <Reference Include="NHibernate, Version=3.3.1.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\..\..\..\lib\nhibernate\NHibernate.dll</HintPath>
     </Reference>
diff --git a/src/Orchard.Web/Modules/SysCache/SysCache.csproj b/src/Orchard.Web/Modules/SysCache/SysCache.csproj
index f4d597833..7bb9cd9cf 100644
--- a/src/Orchard.Web/Modules/SysCache/SysCache.csproj
+++ b/src/Orchard.Web/Modules/SysCache/SysCache.csproj
@@ -47,7 +47,8 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="Microsoft.CSharp" />
-    <Reference Include="NHibernate">
+    <Reference Include="NHibernate, Version=3.3.1.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\..\..\lib\nhibernate\NHibernate.dll</HintPath>
     </Reference>
     <Reference Include="NHibernate.Caches.SysCache2">
diff --git a/src/Orchard.Web/Modules/UpgradeTo16/UpgradeTo16.csproj b/src/Orchard.Web/Modules/UpgradeTo16/UpgradeTo16.csproj
index 293ac98e3..7068df193 100644
--- a/src/Orchard.Web/Modules/UpgradeTo16/UpgradeTo16.csproj
+++ b/src/Orchard.Web/Modules/UpgradeTo16/UpgradeTo16.csproj
@@ -42,7 +42,8 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="Microsoft.CSharp" />
-    <Reference Include="NHibernate">
+    <Reference Include="NHibernate, Version=3.3.1.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\..\..\lib\nhibernate\NHibernate.dll</HintPath>
     </Reference>
     <Reference Include="System" />
diff --git a/src/Orchard/Orchard.Framework.csproj b/src/Orchard/Orchard.Framework.csproj
index 4b3ed765b..5147be3c4 100644
--- a/src/Orchard/Orchard.Framework.csproj
+++ b/src/Orchard/Orchard.Framework.csproj
@@ -89,11 +89,16 @@
       <HintPath>..\..\lib\log4net\log4net.dll</HintPath>
     </Reference>
     <Reference Include="Microsoft.CSharp" />
-    <Reference Include="NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
-      <SpecificVersion>False</SpecificVersion>
-      <HintPath>..\..\lib\nhibernate\NHibernate.dll</HintPath>
+    <Reference Include="Newtonsoft.Json">
+      <HintPath>..\..\lib\newtonsoft.json\Newtonsoft.Json.dll</HintPath>
     </Reference>
-    <Reference Include="NHibernate.Linq">
+    <Reference Include="NHibernate, Version=3.3.1.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4, processorArchitecture=MSIL">
+      <HintPath>..\..\lib\nhibernate\NHibernate.dll</HintPath>
+      <SpecificVersion>False</SpecificVersion>
+      <Private>True</Private>
+    </Reference>
+    <Reference Include="NHibernate.Linq, Version=0.0.0.0, Culture=neutral, processorArchitecture=MSIL">
+      <SpecificVersion>False</SpecificVersion>
       <HintPath>..\..\lib\nhibernate.linq\NHibernate.Linq.dll</HintPath>
     </Reference>
     <Reference Include="System" />