diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 6504da6..a44dfbd 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -42,3 +42,5 @@ jobs:
       run: dotnet build --no-restore
     - name: Test
       run: dotnet test --no-build --verbosity normal 
+      env:
+        RUNON_GITHUB: y
diff --git a/tests/VisualTest/Class1.cs b/tests/VisualTest/Class1.cs
index 0642846..59dd721 100644
--- a/tests/VisualTest/Class1.cs
+++ b/tests/VisualTest/Class1.cs
@@ -1,4 +1,5 @@
-using NUnit.Framework;
+#if !OnGitHubAction
+using NUnit.Framework;
 using System;
 using System.Diagnostics;
 using System.Drawing.Text;
@@ -122,4 +123,5 @@ public void Closing()
             _process.Kill();
         }
     }
-}
\ No newline at end of file
+}
+#endif
\ No newline at end of file
diff --git a/tests/VisualTest/VisualTest.csproj b/tests/VisualTest/VisualTest.csproj
index 8fd9075..52d120d 100644
--- a/tests/VisualTest/VisualTest.csproj
+++ b/tests/VisualTest/VisualTest.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
 
   <PropertyGroup>
-    <TargetFrameworks>net462;net5.0-windows</TargetFrameworks>
+    <TargetFrameworks>netcoreapp3.0;net462;net5.0-windows</TargetFrameworks>
     <UseWPF>true</UseWPF>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
@@ -25,4 +25,8 @@
     </None>
   </ItemGroup>
 
+  <PropertyGroup Condition=" '$(RUNON_GITHUB)' != '' ">
+    <DefineConstants>OnGitHubAction</DefineConstants>
+  </PropertyGroup>
+
 </Project>