diff --git a/samples/interop/GtkInteropDemo/GtkInteropDemo.csproj b/samples/interop/GtkInteropDemo/GtkInteropDemo.csproj
index 044b96c865..0837a6efe5 100644
--- a/samples/interop/GtkInteropDemo/GtkInteropDemo.csproj
+++ b/samples/interop/GtkInteropDemo/GtkInteropDemo.csproj
@@ -149,6 +149,11 @@
       <Name>ControlCatalog</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="System.Reactive">
+      <Version>3.0.0</Version>
+    </PackageReference>
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <Import Project="$(MSBuildThisFileDirectory)..\..\..\src\Shared\nuget.workaround.targets" />
 </Project>
\ No newline at end of file
diff --git a/samples/interop/WindowsInteropTest/WindowsInteropTest.csproj b/samples/interop/WindowsInteropTest/WindowsInteropTest.csproj
index c787ab76ee..22b4e4188c 100644
--- a/samples/interop/WindowsInteropTest/WindowsInteropTest.csproj
+++ b/samples/interop/WindowsInteropTest/WindowsInteropTest.csproj
@@ -179,6 +179,11 @@
       <Generator>MSBuild:Compile</Generator>
     </Page>
   </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="System.Reactive">
+      <Version>3.0.0</Version>
+    </PackageReference>
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <Import Project="$(MSBuildThisFileDirectory)..\..\..\src\Shared\nuget.workaround.targets" />
 </Project>
\ No newline at end of file