diff --git a/sandbox/MessagePackSandbox/MessagePackSandbox.csproj b/sandbox/MessagePackSandbox/MessagePackSandbox.csproj
index 878913c..0f36a73 100644
--- a/sandbox/MessagePackSandbox/MessagePackSandbox.csproj
+++ b/sandbox/MessagePackSandbox/MessagePackSandbox.csproj
@@ -8,7 +8,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="MessagePack" Version="2.5.124" />
+        <PackageReference Include="MessagePack" Version="2.5.129" />
     </ItemGroup>
 
 </Project>