diff --git a/src/UniTask.NetCore/UniTask.NetCore.csproj b/src/UniTask.NetCore/UniTask.NetCore.csproj
index 6b6d81e..1f93aa9 100644
--- a/src/UniTask.NetCore/UniTask.NetCore.csproj
+++ b/src/UniTask.NetCore/UniTask.NetCore.csproj
@@ -23,6 +23,7 @@
         <PackageIcon>Icon.png</PackageIcon>
         <SignAssembly>true</SignAssembly>
         <AssemblyOriginatorKeyFile>opensource.snk</AssemblyOriginatorKeyFile>
+        <IsPackable>true</IsPackable>
     </PropertyGroup>
 
     <ItemGroup>
diff --git a/src/UniTask.NetCoreSandbox/UniTask.NetCoreSandbox.csproj b/src/UniTask.NetCoreSandbox/UniTask.NetCoreSandbox.csproj
index cc33684..369f7ee 100644
--- a/src/UniTask.NetCoreSandbox/UniTask.NetCoreSandbox.csproj
+++ b/src/UniTask.NetCoreSandbox/UniTask.NetCoreSandbox.csproj
@@ -4,6 +4,7 @@
     <OutputType>Exe</OutputType>
     <TargetFramework>netcoreapp3.1</TargetFramework>
     <RootNamespace>NetCoreSandbox</RootNamespace>
+    <IsPackable>false</IsPackable>
   </PropertyGroup>
 
   <ItemGroup>