diff --git a/Directory.Build.targets b/Directory.Build.targets
index 8f38a48cd959e..2cad2d7b596e2 100644
--- a/Directory.Build.targets
+++ b/Directory.Build.targets
@@ -1,5 +1,20 @@
 <!-- Licensed to the .NET Foundation under one or more agreements. The .NET Foundation licenses this file to you under the MIT license. See the LICENSE file in the project root for more information. -->
 <Project>
+  <!-- use the source-built version of the reference packs if building in source-build -->
+  <ItemGroup Condition="'$(DotNetBuildFromSource)' == 'true'">
+    <KnownFrameworkReference Update="Microsoft.NETCore.App">
+      <TargetingPackVersion Condition="'%(TargetFramework)' == 'net6.0'">6.0.0</TargetingPackVersion>
+    </KnownFrameworkReference>
+    <KnownFrameworkReference Update="Microsoft.AspNetCore.App">
+      <TargetingPackVersion Condition="'%(TargetFramework)' == 'net6.0'">6.0.0</TargetingPackVersion>
+    </KnownFrameworkReference>
+  </ItemGroup>
+
+  <!-- do not restore or use the 6.0 app host in source-build -->
+  <PropertyGroup Condition="'$(DotNetBuildFromSource)' == 'true'">
+    <UseAppHost>false</UseAppHost>
+  </PropertyGroup>
+
   <Import Project="Sdk.targets" Sdk="Microsoft.DotNet.Arcade.Sdk" />
   <Import Project="eng\targets\Imports.targets" />
 </Project>