diff --git a/Tester/Tester.csproj b/Tester/Tester.csproj
index ee01ee1..410d644 100644
--- a/Tester/Tester.csproj
+++ b/Tester/Tester.csproj
@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="MessagePack" Version="2.3.75" />
+    <PackageReference Include="MessagePack" Version="2.5.187" />
     <PackageReference Include="System.Drawing.Common" Version="5.0.2" />
   </ItemGroup>