diff --git a/src/WebApiContrib.Core.Formatter.MessagePack/WebApiContrib.Core.Formatter.MessagePack.csproj b/src/WebApiContrib.Core.Formatter.MessagePack/WebApiContrib.Core.Formatter.MessagePack.csproj
index 14d07a9..1b28306 100644
--- a/src/WebApiContrib.Core.Formatter.MessagePack/WebApiContrib.Core.Formatter.MessagePack.csproj
+++ b/src/WebApiContrib.Core.Formatter.MessagePack/WebApiContrib.Core.Formatter.MessagePack.csproj
@@ -13,7 +13,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Core" Version="2.1.3" />
-    <PackageReference Include="MessagePack" Version="1.7.3.4" />
+    <PackageReference Include="MessagePack" Version="1.9.11" />
   </ItemGroup>
 
 </Project>
diff --git a/tests/WebApiContrib.Core.MessagePack.Tests/WebApiContrib.Core.MessagePack.Tests.csproj b/tests/WebApiContrib.Core.MessagePack.Tests/WebApiContrib.Core.MessagePack.Tests.csproj
index f885eaf..0cc7eec 100644
--- a/tests/WebApiContrib.Core.MessagePack.Tests/WebApiContrib.Core.MessagePack.Tests.csproj
+++ b/tests/WebApiContrib.Core.MessagePack.Tests/WebApiContrib.Core.MessagePack.Tests.csproj
@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="MessagePack" Version="1.7.3.4" />
+    <PackageReference Include="MessagePack" Version="1.9.11" />
     <PackageReference Include="Microsoft.AspNetCore.App" Version="2.1.6" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="2.1.3" />
     <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="2.1.1" />