diff --git a/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.Portable.csproj b/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.Portable.csproj
index 55aa3ec71..7e4c50526 100644
--- a/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.Portable.csproj
+++ b/Src/Newtonsoft.Json.Tests/Newtonsoft.Json.Tests.Portable.csproj
@@ -78,7 +78,7 @@
       <HintPath>..\packages\NUnit.2.6.2\lib\nunit.framework.dll</HintPath>
     </Reference>
     <Reference Include="System" />
-    <Reference Include="System.Collections.Immutable, Version=1.1.34.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+    <Reference Include="System.Collections.Immutable, Version=1.1.36.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
       <SpecificVersion>False</SpecificVersion>
       <HintPath>..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
     </Reference>