diff --git a/src/libraries/Directory.Build.targets b/src/libraries/Directory.Build.targets
index b219e7cf41a913..98af9482d49925 100644
--- a/src/libraries/Directory.Build.targets
+++ b/src/libraries/Directory.Build.targets
@@ -170,6 +170,7 @@
   <!-- Adds Nullable annotation attributes to C# non .NETCoreApp builds. -->
   <ItemGroup Condition="'$(Nullable)' != '' and
                         '$(Nullable)' != 'disable' and
+                        '$(NoIncludeNullableAttributes)' != 'true' and
                         '$(MSBuildProjectExtension)' == '.csproj' and
                         '$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\NullableAttributes.cs" Link="System\Diagnostics\CodeAnalysis\NullableAttributes.cs" />
diff --git a/src/libraries/Microsoft.Extensions.Configuration.Binder/tests/SourceGenerationTests/Microsoft.Extensions.Configuration.Binder.SourceGeneration.Tests.csproj b/src/libraries/Microsoft.Extensions.Configuration.Binder/tests/SourceGenerationTests/Microsoft.Extensions.Configuration.Binder.SourceGeneration.Tests.csproj
index eccbe7d759b411..81562ed265caab 100644
--- a/src/libraries/Microsoft.Extensions.Configuration.Binder/tests/SourceGenerationTests/Microsoft.Extensions.Configuration.Binder.SourceGeneration.Tests.csproj
+++ b/src/libraries/Microsoft.Extensions.Configuration.Binder/tests/SourceGenerationTests/Microsoft.Extensions.Configuration.Binder.SourceGeneration.Tests.csproj
@@ -8,6 +8,9 @@
     <NoWarn>$(NoWarn);SYSLIB1103,SYSLIB1104</NoWarn>
     <InterceptorsPreviewNamespaces>$(InterceptorsPreviewNamespaces);Microsoft.Extensions.Configuration.Binder.SourceGeneration</InterceptorsPreviewNamespaces>
     <EnableConfigurationBindingGenerator>true</EnableConfigurationBindingGenerator>
+
+    <!-- Avoid conflict with Microsoft.Extensions.Configuration.Binder (via InternalsVisibleTo) -->
+    <NoIncludeNullableAttributes>true</NoIncludeNullableAttributes>
   </PropertyGroup>
 
   <PropertyGroup>