diff --git a/cs/playground/AsyncStress/AsyncStress.csproj b/cs/playground/AsyncStress/AsyncStress.csproj
index 302a7c8e5..6070a7fc5 100644
--- a/cs/playground/AsyncStress/AsyncStress.csproj
+++ b/cs/playground/AsyncStress/AsyncStress.csproj
@@ -9,7 +9,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="MessagePack" Version="2.5.187" />
+        <PackageReference Include="MessagePack" Version="2.5.301" />
         <PackageReference Include="xunit.assert" Version="2.4.2" />
     </ItemGroup>