diff --git a/Rx.NET/Source/src/Microsoft.Reactive.Testing/Microsoft.Reactive.Testing.csproj b/Rx.NET/Source/src/Microsoft.Reactive.Testing/Microsoft.Reactive.Testing.csproj
index 65ac87715..9c38d36c7 100644
--- a/Rx.NET/Source/src/Microsoft.Reactive.Testing/Microsoft.Reactive.Testing.csproj
+++ b/Rx.NET/Source/src/Microsoft.Reactive.Testing/Microsoft.Reactive.Testing.csproj
@@ -18,7 +18,7 @@
 
   <ItemGroup>
     <EmbeddedResource Include="Properties\*.xml" />
-    <PackageReference Include="xunit.assert.source" Version="2.8.0" PrivateAssets="All" /> 
+    <PackageReference Include="xunit.assert.source" Version="2.9.0" PrivateAssets="All" /> 
     <ProjectReference Include="..\System.Reactive\System.Reactive.csproj" />
   </ItemGroup>