diff --git a/X10D.Tests/X10D.Tests.csproj b/X10D.Tests/X10D.Tests.csproj
index 850a144..327a67e 100644
--- a/X10D.Tests/X10D.Tests.csproj
+++ b/X10D.Tests/X10D.Tests.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net7.0</TargetFramework>
+        <TargetFrameworks>net7.0;net6.0;netcoreapp3.1</TargetFrameworks>
         <LangVersion>11.0</LangVersion>
         <IsPackable>false</IsPackable>
         <Nullable>enable</Nullable>