diff --git a/src/SharpCompress/AssemblyInfo.cs b/src/SharpCompress/AssemblyInfo.cs
index 0270020d..e51d97fe 100644
--- a/src/SharpCompress/AssemblyInfo.cs
+++ b/src/SharpCompress/AssemblyInfo.cs
@@ -1,3 +1,7 @@
 using System;
+using System.Runtime.CompilerServices;
 
 [assembly: CLSCompliant(true)]
+[assembly: InternalsVisibleTo(
+    "SharpCompress.Test,PublicKey=0024000004800000940000000602000000240000525341310004000001000100158bebf1433f76dffc356733c138babea7a47536c65ed8009b16372c6f4edbb20554db74a62687f56b97c20a6ce8c4b123280279e33c894e7b3aa93ab3c573656fde4db576cfe07dba09619ead26375b25d2c4a8e43f7be257d712b0dd2eb546f67adb09281338618a58ac834fc038dd7e2740a7ab3591826252e4f4516306dc"
+)]
diff --git a/src/SharpCompress/NotNullExtensions.cs b/src/SharpCompress/NotNullExtensions.cs
index 7342bd7b..29245114 100644
--- a/src/SharpCompress/NotNullExtensions.cs
+++ b/src/SharpCompress/NotNullExtensions.cs
@@ -6,7 +6,7 @@ using System.Runtime.CompilerServices;
 
 namespace SharpCompress.Helpers;
 
-public static class NotNullExtensions
+internal static class NotNullExtensions
 {
     public static IEnumerable<T> Empty<T>(this IEnumerable<T>? source) =>
         source ?? Enumerable.Empty<T>();
diff --git a/src/SharpCompress/Utility.cs b/src/SharpCompress/Utility.cs
index 6a6aeee7..74974850 100644
--- a/src/SharpCompress/Utility.cs
+++ b/src/SharpCompress/Utility.cs
@@ -9,8 +9,7 @@ using SharpCompress.Readers;
 
 namespace SharpCompress.Helpers;
 
-[CLSCompliant(false)]
-public static class Utility
+internal static class Utility
 {
     public static ReadOnlyCollection<T> ToReadOnly<T>(this IList<T> items) => new(items);
 
diff --git a/tests/SharpCompress.Test/SharpCompress.Test.csproj b/tests/SharpCompress.Test/SharpCompress.Test.csproj
index 3bfeaa3e..a47b2174 100644
--- a/tests/SharpCompress.Test/SharpCompress.Test.csproj
+++ b/tests/SharpCompress.Test/SharpCompress.Test.csproj
@@ -3,6 +3,8 @@
     <TargetFrameworks>net8.0;net462</TargetFrameworks>
     <AssemblyName>SharpCompress.Test</AssemblyName>
     <PackageId>SharpCompress.Test</PackageId>
+    <AssemblyOriginatorKeyFile>SharpCompress.Test.snk</AssemblyOriginatorKeyFile>
+    <SignAssembly>true</SignAssembly>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\SharpCompress\SharpCompress.csproj" />
diff --git a/tests/SharpCompress.Test/SharpCompress.Test.snk b/tests/SharpCompress.Test/SharpCompress.Test.snk
new file mode 100644
index 00000000..5a9ce097
Binary files /dev/null and b/tests/SharpCompress.Test/SharpCompress.Test.snk differ