Fixing compilation
diff --git a/src/Lucene.Net.Core/Lucene.Net.csproj b/src/Lucene.Net.Core/Lucene.Net.csproj
index 62ba04c..51b08af 100644
--- a/src/Lucene.Net.Core/Lucene.Net.csproj
+++ b/src/Lucene.Net.Core/Lucene.Net.csproj
@@ -39,6 +39,10 @@
<ItemGroup>
<Reference Include="Microsoft.CSharp" />
<Reference Include="System" />
+ <Reference Include="System.Collections.Immutable, Version=1.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+ <HintPath>..\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+ <Private>True</Private>
+ </Reference>
<Reference Include="System.configuration" />
<Reference Include="System.Core" />
<Reference Include="System.Data" />
diff --git a/src/Lucene.Net.Core/packages.config b/src/Lucene.Net.Core/packages.config
index 6b8deb9..5d1cb40 100644
--- a/src/Lucene.Net.Core/packages.config
+++ b/src/Lucene.Net.Core/packages.config
@@ -1,3 +1,4 @@
<?xml version="1.0" encoding="utf-8"?>
<packages>
+ <package id="System.Collections.Immutable" version="1.2.0" targetFramework="net451" />
</packages>
\ No newline at end of file