diff --git a/Rx.NET/Integration/LinuxTests/LinuxTests.csproj b/Rx.NET/Integration/LinuxTests/LinuxTests.csproj
index 10fed3522c..585b989f12 100644
--- a/Rx.NET/Integration/LinuxTests/LinuxTests.csproj
+++ b/Rx.NET/Integration/LinuxTests/LinuxTests.csproj
@@ -24,11 +24,11 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />    
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
-    <PackageReference Include="System.Reactive" Version="4.2.0-preview.63" />
-    <PackageReference Include="Microsoft.Reactive.Testing" Version="4.2.0-preview.63" />
-    <PackageReference Include="System.Reactive.Observable.Aliases" Version="4.2.0-preview.63" />
+    <PackageReference Include="System.Reactive" Version="5.1.0-preview*" />
+    <PackageReference Include="Microsoft.Reactive.Testing" Version="5.1.0-preview*" />
+    <PackageReference Include="System.Reactive.Observable.Aliases" Version="5.1.0-preview*" />
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/Rx.NET/Integration/WindowsDesktopTests/WindowsDesktopTests.csproj b/Rx.NET/Integration/WindowsDesktopTests/WindowsDesktopTests.csproj
index 15386004d7..6dedc757a4 100644
--- a/Rx.NET/Integration/WindowsDesktopTests/WindowsDesktopTests.csproj
+++ b/Rx.NET/Integration/WindowsDesktopTests/WindowsDesktopTests.csproj
@@ -29,11 +29,11 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />    
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.1" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
-    <PackageReference Include="System.Reactive" Version="4.2.0-preview.63" />
-    <PackageReference Include="Microsoft.Reactive.Testing" Version="4.2.0-preview.63" />
-    <PackageReference Include="System.Reactive.Observable.Aliases" Version="4.2.0-preview.63" />
+    <PackageReference Include="System.Reactive" Version="5.1.0-preview*" />
+    <PackageReference Include="Microsoft.Reactive.Testing" Version="5.1.0-preview*" />
+    <PackageReference Include="System.Reactive.Observable.Aliases" Version="5.1.0-preview*" />
   </ItemGroup>
 </Project>
\ No newline at end of file