diff --git a/Octokit.Reactive/Octokit.Reactive.csproj b/Octokit.Reactive/Octokit.Reactive.csproj
index a3f7eec1..a9097a4b 100644
--- a/Octokit.Reactive/Octokit.Reactive.csproj
+++ b/Octokit.Reactive/Octokit.Reactive.csproj
@@ -56,6 +56,7 @@
   <ItemGroup Condition=" '$(TargetFramework)' == 'net45' or  '$(TargetFramework)' == 'net46'  ">
     <Reference Include="System" />
     <Reference Include="Microsoft.CSharp" />
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0" PrivateAssets="All" />
   </ItemGroup>
 
 </Project>
diff --git a/Octokit.Tests.Conventions/Octokit.Tests.Conventions.csproj b/Octokit.Tests.Conventions/Octokit.Tests.Conventions.csproj
index 1328bc84..0dd686c2 100644
--- a/Octokit.Tests.Conventions/Octokit.Tests.Conventions.csproj
+++ b/Octokit.Tests.Conventions/Octokit.Tests.Conventions.csproj
@@ -40,6 +40,10 @@
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
   </ItemGroup>
 
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0"  PrivateAssets="All" />
+  </ItemGroup>
+
   <ItemGroup>
     <Service Include="{82a7f48d-3b50-4b1e-b82e-3ada8210c358}" />
   </ItemGroup>
diff --git a/Octokit.Tests.Integration/Octokit.Tests.Integration.csproj b/Octokit.Tests.Integration/Octokit.Tests.Integration.csproj
index 1a3eaf34..1e003a8a 100644
--- a/Octokit.Tests.Integration/Octokit.Tests.Integration.csproj
+++ b/Octokit.Tests.Integration/Octokit.Tests.Integration.csproj
@@ -53,4 +53,8 @@
     </PackageReference>
   </ItemGroup>
 
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0"  PrivateAssets="All" />
+  </ItemGroup>
+
 </Project>
diff --git a/Octokit.Tests/Octokit.Tests.csproj b/Octokit.Tests/Octokit.Tests.csproj
index 5335be34..cada2a7c 100644
--- a/Octokit.Tests/Octokit.Tests.csproj
+++ b/Octokit.Tests/Octokit.Tests.csproj
@@ -47,6 +47,7 @@
   <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">
     <Reference Include="System" />
     <Reference Include="Microsoft.CSharp" />
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0" PrivateAssets="All" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/Octokit/Octokit.csproj b/Octokit/Octokit.csproj
index ecab0718..be6e2872 100644
--- a/Octokit/Octokit.csproj
+++ b/Octokit/Octokit.csproj
@@ -46,6 +46,7 @@
     <Reference Include="System.Net.Http" />
     <Reference Include="System" />
     <Reference Include="Microsoft.CSharp" />
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0" PrivateAssets="All" />
   </ItemGroup>
 
   <ItemGroup>