diff --git a/fcs/FSharp.Compiler.Service.Tests/App.config b/fcs/FSharp.Compiler.Service.Tests/App.config
index 76cc57718b..1e7989fe8c 100644
--- a/fcs/FSharp.Compiler.Service.Tests/App.config
+++ b/fcs/FSharp.Compiler.Service.Tests/App.config
@@ -7,6 +7,10 @@
         <assemblyIdentity name="FSharp.Core" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
         <bindingRedirect oldVersion="2.0.0.0-4.4.0.0" newVersion="4.4.1.0" />
       </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+        <bindingRedirect oldVersion="1.0.0.0-1.2.0.0" newVersion="1.2.1.0" />
+      </dependentAssembly>
     </assemblyBinding>
   </runtime>
   <startup>
diff --git a/fcs/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj b/fcs/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj
index 95498ca69c..1cd80fda4e 100644
--- a/fcs/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj
+++ b/fcs/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj
@@ -100,7 +100,7 @@
   
   <ItemGroup>
     <Reference Include="System.Collections.Immutable">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
       <Private>True</Private>
     </Reference>
     <Reference Include="nunit.framework">
diff --git a/fcs/FSharp.Compiler.Service/FSharp.Compiler.Service.fsproj b/fcs/FSharp.Compiler.Service/FSharp.Compiler.Service.fsproj
index 99611113df..639fc87525 100644
--- a/fcs/FSharp.Compiler.Service/FSharp.Compiler.Service.fsproj
+++ b/fcs/FSharp.Compiler.Service/FSharp.Compiler.Service.fsproj
@@ -626,7 +626,7 @@
       <HintPath>$(FSharpSourcesRoot)\..\packages\System.Reflection.Metadata.1.4.2\lib\portable-net45+win8\System.Reflection.Metadata.dll</HintPath>
     </Reference>
     <Reference Include="System.Collections.Immutable">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.3.1\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
     </Reference>
     <Reference Include="System.ValueTuple">
       <HintPath>$(FSharpSourcesRoot)\..\packages\System.ValueTuple.4.3.1\lib\netstandard1.0\System.ValueTuple.dll</HintPath>
diff --git a/fcs/docsrc/content/corelib.fsx b/fcs/docsrc/content/corelib.fsx
index 6ec522f316..e7959385f8 100644
--- a/fcs/docsrc/content/corelib.fsx
+++ b/fcs/docsrc/content/corelib.fsx
@@ -19,19 +19,25 @@ an FSharp.Core.optdata and FSharp.Core.sigdata, see below for guidance.
 Binding redirects for your application
 --------------------------------------
 
-The FSharp.Compiler.Service.dll component depends on FSharp.Core 4.3.0.0.  Normally your application will target
+The FSharp.Compiler.Service.dll component depends on FSharp.Core 4.4.0.0.  Normally your application will target
 a later version of FSharp.Core, and you will need a [binding redirect](http://msdn.microsoft.com/en-us/library/7wd6ex19(v=vs.110).aspx) to ensure
-that FSharp.Core 4.3.0.0 forwards to which the final version of FSharp.Core.dll your application uses.
+that other versions of FSharp.Core forward to the final version of FSharp.Core.dll your application uses.
 Binding redirect files are normally generated automatically by build tools. If not, you can use one like this
 (if your tool is called ``HostedCompiler.exe``, the binding redirect file is called ``HostedCompiler.exe.config``)
 
+Some other dependencies may also need to be reconciled and forwarded.
+
     <?xml version="1.0" encoding="utf-8" ?>
     <configuration>
         <runtime>
           <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
             <dependentAssembly>
               <assemblyIdentity name="FSharp.Core" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
-              <bindingRedirect oldVersion="2.0.0.0-4.3.0.0" newVersion="4.3.1.0"/>
+              <bindingRedirect oldVersion="2.0.0.0-4.4.0.0" newVersion="4.4.1.0"/>
+            </dependentAssembly>
+            <dependentAssembly>
+              <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+              <bindingRedirect oldVersion="1.0.0.0-1.2.0.0" newVersion="1.2.1.0" />
             </dependentAssembly>
           </assemblyBinding>
         </runtime>	
diff --git a/fcs/docsrc/content/ja/corelib.fsx b/fcs/docsrc/content/ja/corelib.fsx
index 40d3dbcd51..e2189faaea 100644
--- a/fcs/docsrc/content/ja/corelib.fsx
+++ b/fcs/docsrc/content/ja/corelib.fsx
@@ -26,6 +26,10 @@ FSharp.Compiler.Service.dll コンポーネントは FSharp.Core 4.3.0.0 に依
               <assemblyIdentity name="FSharp.Core" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
               <bindingRedirect oldVersion="2.0.0.0-4.3.0.0" newVersion="4.3.1.0"/>
             </dependentAssembly>
+            <dependentAssembly>
+              <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+              <bindingRedirect oldVersion="1.0.0.0-1.2.0.0" newVersion="1.2.1.0" />
+            </dependentAssembly>
           </assemblyBinding>
         </runtime>	
     </configuration>
diff --git a/fcs/nuget/FSharp.Compiler.Service.nuspec b/fcs/nuget/FSharp.Compiler.Service.nuspec
index 5b05dba395..bfb19e2661 100644
--- a/fcs/nuget/FSharp.Compiler.Service.nuspec
+++ b/fcs/nuget/FSharp.Compiler.Service.nuspec
@@ -19,7 +19,7 @@
         <summary>F# compiler services for creating IDE tools, language extensions and for F# embedding.</summary>
         <dependencies>
             <group targetFramework="net45">
-                <dependency id="System.Collections.Immutable" version="1.2.0" />
+                <dependency id="System.Collections.Immutable" version="1.3.1" />
                 <dependency id="System.Reflection.Metadata" version="1.4.2" />
             </group>
         </dependencies>
diff --git a/fcs/samples/EditorService/App.config b/fcs/samples/EditorService/App.config
index 677f8d8685..c923cce5cf 100644
--- a/fcs/samples/EditorService/App.config
+++ b/fcs/samples/EditorService/App.config
@@ -7,15 +7,7 @@
     <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
       <dependentAssembly>
         <assemblyIdentity name="FSharp.Core" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
-        <bindingRedirect oldVersion="2.0.0.0" newVersion="4.3.1.0" />
-        <bindingRedirect oldVersion="2.3.0.0" newVersion="4.3.1.0" />
-        <bindingRedirect oldVersion="2.3.5.0" newVersion="4.3.1.0" />
-        <bindingRedirect oldVersion="4.0.0.0" newVersion="4.3.1.0" />
-        <bindingRedirect oldVersion="4.3.0.0" newVersion="4.3.1.0" />
-        <bindingRedirect oldVersion="3.3.1.0" newVersion="4.3.1.0" />
-        <bindingRedirect oldVersion="2.3.5.1" newVersion="4.3.1.0" />
-        <bindingRedirect oldVersion="3.78.3.1" newVersion="4.3.1.0" />
-        <bindingRedirect oldVersion="3.259.3.1" newVersion="4.3.1.0" />
+        <bindingRedirect oldVersion="2.0.0.0-4.4.0.0" newVersion="4.4.1.0" />
       </dependentAssembly>
     </assemblyBinding>
   </runtime>
diff --git a/fcs/samples/EditorService/EditorService.fsproj b/fcs/samples/EditorService/EditorService.fsproj
index 7daef7d9b5..71df0f34d2 100644
--- a/fcs/samples/EditorService/EditorService.fsproj
+++ b/fcs/samples/EditorService/EditorService.fsproj
@@ -12,7 +12,6 @@
     <AssemblyName>EditorService</AssemblyName>
     <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
     <Name>EditorService</Name>
-    <TargetFSharpCoreVersion>4.4.0.0</TargetFSharpCoreVersion>
     <TargetFrameworkProfile />
     <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
   </PropertyGroup>
diff --git a/packages.config b/packages.config
index 57ee60f4b1..8a0d01eaae 100644
--- a/packages.config
+++ b/packages.config
@@ -12,7 +12,7 @@
   <package id="MicroBuild.Core.Sentinel" version="1.0.0" />
 
   <!-- Actual dependencies of FSharp.Compiler.dll and FSharp.Core.dll -->
-  <package id="System.Collections.Immutable" version="1.2.0" />
+  <package id="System.Collections.Immutable" version="1.3.1" />
   <package id="System.Reflection.Metadata" version="1.4.2" />
   <package id="Microsoft.DiaSymReader.PortablePdb" version="1.1.0"  />
   <package id="Microsoft.DiaSymReader" version="1.1.0" />
diff --git a/setup/FSharp.SDK/component-groups/Compiler_Redist.wxs b/setup/FSharp.SDK/component-groups/Compiler_Redist.wxs
index ae8a46aad6..78ed928905 100644
--- a/setup/FSharp.SDK/component-groups/Compiler_Redist.wxs
+++ b/setup/FSharp.SDK/component-groups/Compiler_Redist.wxs
@@ -171,7 +171,7 @@
       </Component>
 
       <Component Id="Compiler_Redist_System.Collections.Immutable.dll" Guid="$(fsharp.guid(Compiler_Redist_System.Collections.Immutable.dll, $(var.LocaleCode)))">
-        <File Id="Compiler_Redist_System.Collections.Immutable.dll" Source="$(var.NugetPackagesDir)\System.Collections.Immutable.1.2.0\lib\netstandard1.0\System.Collections.Immutable.dll" />
+        <File Id="Compiler_Redist_System.Collections.Immutable.dll" Source="$(var.NugetPackagesDir)\System.Collections.Immutable.1.3.1\lib\netstandard1.0\System.Collections.Immutable.dll" />
       </Component>
 
       <Component Id="Compiler_Redist_System.Reflection.Metadata.dll" Guid="$(fsharp.guid(Compiler_Redist_System.Reflection.Metadata.dll, $(var.LocaleCode)))">
diff --git a/setup/packages.config b/setup/packages.config
index b2376a2008..aded14292c 100644
--- a/setup/packages.config
+++ b/setup/packages.config
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="System.Collections.Immutable" version="1.2.0" />
+  <package id="System.Collections.Immutable" version="1.3.1" />
   <package id="System.Reflection.Metadata" version="1.4.1-beta-24227-04" />
   <package id="Microsoft.DiaSymReader.PortablePdb" version="1.1.0"  />
   <package id="Microsoft.DiaSymReader" version="1.0.8" />
diff --git a/src/FSharpSource.Settings.targets b/src/FSharpSource.Settings.targets
index 718817a879..11a1cd12bd 100644
--- a/src/FSharpSource.Settings.targets
+++ b/src/FSharpSource.Settings.targets
@@ -35,6 +35,7 @@
     <RoslynVersion>2.3.0-beta2-61719-01</RoslynVersion>
     <RoslynVSBinariesVersion>15.0</RoslynVSBinariesVersion>
     <RoslynVSPackagesVersion>15.0.26201</RoslynVSPackagesVersion>
+    <SystemCollectionsImmutableVersion>1.3.1</SystemCollectionsImmutableVersion>
     <VSSDK_BUILDTOOLS_VERSION>Microsoft.VSSDK.BuildTools.15.0.26201</VSSDK_BUILDTOOLS_VERSION>
 
     <MicrosoftVisualStudioThreadingVersion>15.3.23</MicrosoftVisualStudioThreadingVersion>
diff --git a/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.BuildFromSource.fsproj b/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.BuildFromSource.fsproj
index 75b2fac99e..655965d3f9 100644
--- a/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.BuildFromSource.fsproj
+++ b/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.BuildFromSource.fsproj
@@ -608,7 +608,7 @@
   <Import Project = "$(MSBuildThisFileDirectory)../../FSharpSource.BuildFromSource.targets" />
 
 <!--
-    "System.Collections.Immutable":"1.2.0",
+    "System.Collections.Immutable":"1.3.1",
     "System.Diagnostics.Process": "4.3.0",
     "System.Diagnostics.TraceSource": "4.3.0",
     "System.Linq.Expressions": "4.3.0",
@@ -630,7 +630,7 @@
 -->
   <ItemGroup>
     <ProjectReference Include="$(MSBuildThisFileDirectory)..\FSharp.Core\FSharp.Core.BuildFromSource.fsproj" />
-    <PackageReference Include="System.Collections.Immutable" Version="1.2.0"></PackageReference>
+    <PackageReference Include="System.Collections.Immutable" Version="1.3.1"></PackageReference>
     <PackageReference Include="System.Diagnostics.Process" Version="4.3.0"></PackageReference>
     <PackageReference Include="System.Diagnostics.TraceSource" Version="4.3.0"></PackageReference>
     <PackageReference Include="System.Linq.Expressions" Version="4.3.0"></PackageReference>
diff --git a/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.fsproj b/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.fsproj
index 10e0f26c59..acfb28e533 100644
--- a/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.fsproj
+++ b/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.fsproj
@@ -663,7 +663,7 @@
       <HintPath>..\..\..\packages\System.Reflection.Metadata.1.4.2\lib\portable-net45+win8\System.Reflection.Metadata.dll</HintPath>
     </Reference>
     <Reference Include="System.Collections.Immutable">
-      <HintPath>..\..\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+      <HintPath>..\..\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
     </Reference>
     <Reference Include="System.ValueTuple">
       <HintPath>..\..\..\packages\System.ValueTuple.4.3.1\lib\netstandard1.0\System.ValueTuple.dll</HintPath>
diff --git a/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.netcore.nuspec b/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.netcore.nuspec
index 8dfb2b6c25..302e10bbe2 100644
--- a/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.netcore.nuspec
+++ b/src/fsharp/FSharp.Compiler.Private/FSharp.Compiler.Private.netcore.nuspec
@@ -16,7 +16,7 @@
         <dependencies>
             <group>
                 <dependency id="NETStandard.Library" version="1.6.0" />
-                <dependency id="System.Collections.Immutable" version="1.2.0" />
+                <dependency id="System.Collections.Immutable" version="1.3.1" />
                 <dependency id="System.Diagnostics.Process" version="4.1.0" />
                 <dependency id="System.Diagnostics.TraceSource" version="4.0.0" />
                 <dependency id="System.Linq.Expressions" version="4.1.0" />
diff --git a/src/fsharp/FSharp.Compiler.Private/project.json b/src/fsharp/FSharp.Compiler.Private/project.json
index c50e8438f9..bee86e2f41 100644
--- a/src/fsharp/FSharp.Compiler.Private/project.json
+++ b/src/fsharp/FSharp.Compiler.Private/project.json
@@ -1,7 +1,7 @@
 {
   "dependencies": {
     "NETStandard.Library": "1.6.1",
-    "System.Collections.Immutable":"1.2.0",
+    "System.Collections.Immutable":"1.3.1",
     "System.Diagnostics.Process": "4.3.0",
     "System.Diagnostics.TraceSource": "4.3.0",
     "System.Linq.Expressions": "4.3.0",
diff --git a/src/fsharp/FSharp.Compiler.nuget/Microsoft.FSharp.Compiler.nuspec b/src/fsharp/FSharp.Compiler.nuget/Microsoft.FSharp.Compiler.nuspec
index f75b32320c..bf3b7397d7 100644
--- a/src/fsharp/FSharp.Compiler.nuget/Microsoft.FSharp.Compiler.nuspec
+++ b/src/fsharp/FSharp.Compiler.nuget/Microsoft.FSharp.Compiler.nuspec
@@ -17,7 +17,7 @@
             <group targetFramework=".NETStandard1.6">
                 <dependency id="Microsoft.NETCore.Platforms" version="1.0.1" />
                 <dependency id="NETStandard.Library" version="1.6.0" />
-                <dependency id="System.Collections.Immutable" version="1.2.0" />
+                <dependency id="System.Collections.Immutable" version="1.3.1" />
                 <dependency id="System.Console" version="4.0.0" />
                 <dependency id="System.Diagnostics.Process" version="4.1.0" />
                 <dependency id="System.Diagnostics.TraceSource" version="4.0.0" />
diff --git a/src/fsharp/FSharp.Compiler.nuget/Testing.FSharp.Compiler.nuspec b/src/fsharp/FSharp.Compiler.nuget/Testing.FSharp.Compiler.nuspec
index ff32c71716..ac1069ee47 100644
--- a/src/fsharp/FSharp.Compiler.nuget/Testing.FSharp.Compiler.nuspec
+++ b/src/fsharp/FSharp.Compiler.nuget/Testing.FSharp.Compiler.nuspec
@@ -16,7 +16,7 @@
             <group targetFramework=".NETStandard1.6">
                 <dependency id="Microsoft.NETCore.Platforms" version="1.0.1" />
                 <dependency id="NETStandard.Library" version="1.6.0" />
-                <dependency id="System.Collections.Immutable" version="1.2.0" />
+                <dependency id="System.Collections.Immutable" version="1.3.1" />
                 <dependency id="System.Console" version="4.0.0" />
                 <dependency id="System.Diagnostics.Process" version="4.1.0" />
                 <dependency id="System.Diagnostics.TraceSource" version="4.0.0" />
diff --git a/src/fsharp/Fsc-proto/Fsc-proto.fsproj b/src/fsharp/Fsc-proto/Fsc-proto.fsproj
index 7b554d80c8..fb99ce70c2 100644
--- a/src/fsharp/Fsc-proto/Fsc-proto.fsproj
+++ b/src/fsharp/Fsc-proto/Fsc-proto.fsproj
@@ -465,7 +465,7 @@
       <HintPath>$(FSharpSourcesRoot)\..\packages\System.Reflection.Metadata.1.4.2\lib\portable-net45+win8\System.Reflection.Metadata.dll</HintPath>
     </Reference>
     <Reference Include="System.Collections.Immutable">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
     </Reference>
     <Reference Include="System.ValueTuple">
       <HintPath>$(FSharpSourcesRoot)\..\packages\System.ValueTuple.4.3.1\lib\netstandard1.0\System.ValueTuple.dll</HintPath>
diff --git a/src/fsharp/Fsc-proto/fsc-proto.exe.config b/src/fsharp/Fsc-proto/fsc-proto.exe.config
index dc90fef34d..46b5e39962 100644
--- a/src/fsharp/Fsc-proto/fsc-proto.exe.config
+++ b/src/fsharp/Fsc-proto/fsc-proto.exe.config
@@ -1,5 +1,11 @@
 <configuration>
    <runtime>
       <gcServer enabled="true"/>
+      <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
+        <dependentAssembly>
+          <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+          <bindingRedirect oldVersion="1.0.0.0-1.2.0.0" newVersion="1.2.1.0" />
+        </dependentAssembly>
+      </assemblyBinding>
    </runtime>
 </configuration>
diff --git a/src/fsharp/Fsc/fsc.exe.config b/src/fsharp/Fsc/fsc.exe.config
index b634d92c0b..493b8a7276 100644
--- a/src/fsharp/Fsc/fsc.exe.config
+++ b/src/fsharp/Fsc/fsc.exe.config
@@ -8,6 +8,10 @@
         <assemblyIdentity name="FSharp.Core" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
         <bindingRedirect oldVersion="2.0.0.0-4.4.1.0" newVersion="4.4.1.0"/>
       </dependentAssembly>
+        <dependentAssembly>
+          <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+          <bindingRedirect oldVersion="1.0.0.0-1.2.0.0" newVersion="1.2.1.0" />
+        </dependentAssembly>
     </assemblyBinding>
   </runtime>
 </configuration>
diff --git a/src/fsharp/fsi/fsi.exe.config b/src/fsharp/fsi/fsi.exe.config
index 61ea7d7f6e..6ae94a8e65 100644
--- a/src/fsharp/fsi/fsi.exe.config
+++ b/src/fsharp/fsi/fsi.exe.config
@@ -7,6 +7,10 @@
         <assemblyIdentity name="FSharp.Core" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
         <bindingRedirect oldVersion="2.0.0.0-4.4.1.0" newVersion="4.4.1.0"/>
       </dependentAssembly>
+        <dependentAssembly>
+          <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+          <bindingRedirect oldVersion="1.0.0.0-1.2.0.0" newVersion="1.2.1.0" />
+        </dependentAssembly>
     </assemblyBinding>
   </runtime>
 </configuration>
diff --git a/src/fsharp/fsi/fsiAnyCpu.exe.config b/src/fsharp/fsi/fsiAnyCpu.exe.config
index 494cb3e584..1308027da2 100644
--- a/src/fsharp/fsi/fsiAnyCpu.exe.config
+++ b/src/fsharp/fsi/fsiAnyCpu.exe.config
@@ -8,6 +8,10 @@
         <assemblyIdentity name="FSharp.Core" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
         <bindingRedirect oldVersion="2.0.0.0-4.4.1.0" newVersion="4.4.1.0"/>
       </dependentAssembly>
+        <dependentAssembly>
+          <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+          <bindingRedirect oldVersion="1.0.0.0-1.2.0.0" newVersion="1.2.1.0" />
+        </dependentAssembly>
     </assemblyBinding>
   </runtime>
 </configuration>
diff --git a/vsintegration/Vsix/VisualFSharpFull/VisualFSharpFull.csproj b/vsintegration/Vsix/VisualFSharpFull/VisualFSharpFull.csproj
index 97218f9922..44881cedb7 100644
--- a/vsintegration/Vsix/VisualFSharpFull/VisualFSharpFull.csproj
+++ b/vsintegration/Vsix/VisualFSharpFull/VisualFSharpFull.csproj
@@ -325,11 +325,6 @@
       <SpecificVersion>False</SpecificVersion>
       <HintPath>$(FSharpSourcesRoot)\..\packages\Newtonsoft.Json.10.0.2\lib\net45\Newtonsoft.Json.dll</HintPath>
     </Reference>
-    <!-- Microsoft.CodeAnalysis.Features requires 1.2.1 but the rest of F# uses 1.2.0 -->
-    <!-- If we don't get the version right here the wrong version is copied during the build  -->
-    <Reference Include="System.Collections.Immutable, Version=1.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
-    </Reference>
   </ItemGroup>
   <Import Project="$(FSharpSourcesRoot)\..\vsintegration\src\FSharp.tools.targets" />
   <Import Project="$(FSharpSourcesRoot)\Microbuild.Settings.targets" />
diff --git a/vsintegration/Vsix/VisualFSharpOpenSource/VisualFSharpOpenSource.csproj b/vsintegration/Vsix/VisualFSharpOpenSource/VisualFSharpOpenSource.csproj
index de084fad4f..3b9fad0cd9 100644
--- a/vsintegration/Vsix/VisualFSharpOpenSource/VisualFSharpOpenSource.csproj
+++ b/vsintegration/Vsix/VisualFSharpOpenSource/VisualFSharpOpenSource.csproj
@@ -324,10 +324,8 @@
       <SpecificVersion>False</SpecificVersion>
       <HintPath>$(FSharpSourcesRoot)\..\packages\Newtonsoft.Json.10.0.2\lib\net45\Newtonsoft.Json.dll</HintPath>
     </Reference>
-    <!-- Microsoft.CodeAnalysis.Features requires 1.2.1 but the rest of F# uses 1.2.0 -->
-    <!-- If we don't get the version right here the wrong version is copied during the build  -->
-    <Reference Include="System.Collections.Immutable, Version=1.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+    <Reference Include="System.Collections.Immutable, Version=1.3.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
     </Reference>
   </ItemGroup>
   <Import Project="$(FSharpSourcesRoot)\..\vsintegration\src\FSharp.tools.targets" />
diff --git a/vsintegration/src/FSharp.Editor/FSharp.Editor.fsproj b/vsintegration/src/FSharp.Editor/FSharp.Editor.fsproj
index a6403bcfaa..bde8237c08 100644
--- a/vsintegration/src/FSharp.Editor/FSharp.Editor.fsproj
+++ b/vsintegration/src/FSharp.Editor/FSharp.Editor.fsproj
@@ -268,7 +268,7 @@
       <Private>True</Private>
     </Reference>
     <Reference Include="System.Collections.Immutable">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
       <Private>True</Private>
     </Reference>
     <Reference Include="Newtonsoft.Json">
diff --git a/vsintegration/src/FSharp.LanguageService.Base/FSharp.LanguageService.Base.csproj b/vsintegration/src/FSharp.LanguageService.Base/FSharp.LanguageService.Base.csproj
index 3c08e86fe1..f8121a8f34 100644
--- a/vsintegration/src/FSharp.LanguageService.Base/FSharp.LanguageService.Base.csproj
+++ b/vsintegration/src/FSharp.LanguageService.Base/FSharp.LanguageService.Base.csproj
@@ -178,7 +178,7 @@
       <HintPath>$(FSharpSourcesRoot)\..\packages\Microsoft.VisualStudio.ComponentModelHost.15.0.26201-alpha\lib\net46\Microsoft.VisualStudio.ComponentModelHost.dll</HintPath>
     </Reference>
     <Reference Include="System.Collections.Immutable">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
       <Private>True</Private>
     </Reference>
     <ProjectReference Include="$(FSharpSourcesRoot)\fsharp\FSharp.Core\FSharp.Core.fsproj">
diff --git a/vsintegration/src/FSharp.LanguageService/FSharp.LanguageService.fsproj b/vsintegration/src/FSharp.LanguageService/FSharp.LanguageService.fsproj
index 28e76eebe5..96ed9e9404 100644
--- a/vsintegration/src/FSharp.LanguageService/FSharp.LanguageService.fsproj
+++ b/vsintegration/src/FSharp.LanguageService/FSharp.LanguageService.fsproj
@@ -239,7 +239,7 @@
       <Private>True</Private>
     </Reference>
     <Reference Include="System.Collections.Immutable">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
       <Private>True</Private>
     </Reference>
   </ItemGroup>
diff --git a/vsintegration/src/FSharp.ProjectSystem.FSharp/ProjectSystem.fsproj b/vsintegration/src/FSharp.ProjectSystem.FSharp/ProjectSystem.fsproj
index df3461eb7b..077dbc4d30 100644
--- a/vsintegration/src/FSharp.ProjectSystem.FSharp/ProjectSystem.fsproj
+++ b/vsintegration/src/FSharp.ProjectSystem.FSharp/ProjectSystem.fsproj
@@ -211,10 +211,8 @@
     <Reference Include="Microsoft.VisualStudio.Shell.$(RoslynVSBinariesVersion), Version=$(RoslynVSBinariesVersion).0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a">
       <HintPath>$(FSharpSourcesRoot)\..\packages\Microsoft.VisualStudio.Shell.$(RoslynVSBinariesVersion).$(RoslynVSPackagesVersion)\lib\Microsoft.VisualStudio.Shell.$(RoslynVSBinariesVersion).dll</HintPath>
     </Reference>
-    <!-- Microsoft.CodeAnalysis.Features requires 1.2.1 but the rest of F# uses 1.2.0 -->
-    <!-- If we don't get the version right here the wrong version is copied during the build  -->
-    <Reference Include="System.Collections.Immutable, Version=1.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+    <Reference Include="System.Collections.Immutable, Version=1.2.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
     </Reference>
     <ProjectReference Include="$(FSharpSourcesRoot)\fsharp\FSharp.Compiler.Private\FSharp.Compiler.Private.fsproj">
       <Project>{2E4D67B4-522D-4CF7-97E4-BA940F0B18F3}</Project>
diff --git a/vsintegration/tests/unittests/VisualFSharp.Unittests.dll.config b/vsintegration/tests/unittests/VisualFSharp.Unittests.dll.config
index e4a42b8fd0..7f55b7d12f 100644
--- a/vsintegration/tests/unittests/VisualFSharp.Unittests.dll.config
+++ b/vsintegration/tests/unittests/VisualFSharp.Unittests.dll.config
@@ -47,10 +47,9 @@
         <assemblyIdentity name="Microsoft.VisualStudio.Platform.VSEditor.Interop" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
         <bindingRedirect oldVersion="14.0.0.0-15.0.0.0" newVersion="15.0.0.0" />
       </dependentAssembly>
-      <!-- Microsoft.CodeAnalysis.Features requires 1.2.1 but the rest of F# uses 1.2.0 -->
       <dependentAssembly>
         <assemblyIdentity name="System.Collections.Immutable" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
-        <bindingRedirect oldVersion="1.0.0.0-1.2.1.0" newVersion="1.2.0.0" />
+        <bindingRedirect oldVersion="1.0.0.0-1.2.0.0" newVersion="1.2.1.0" />
       </dependentAssembly>
     </assemblyBinding>
   </runtime>
diff --git a/vsintegration/tests/unittests/VisualFSharp.Unittests.fsproj b/vsintegration/tests/unittests/VisualFSharp.Unittests.fsproj
index 007ec01e1c..5603dd8058 100644
--- a/vsintegration/tests/unittests/VisualFSharp.Unittests.fsproj
+++ b/vsintegration/tests/unittests/VisualFSharp.Unittests.fsproj
@@ -336,7 +336,7 @@
       <Private>True</Private>
     </Reference>
     <Reference Include="System.Collections.Immutable">
-      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.1.2.0\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
+      <HintPath>$(FSharpSourcesRoot)\..\packages\System.Collections.Immutable.$(SystemCollectionsImmutableVersion)\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
       <Private>True</Private>
     </Reference>
     <ProjectReference Include="$(FSharpSourcesRoot)\fsharp\FSharp.Core\FSharp.Core.fsproj">