diff --git a/src/IndentingBuilder/IndentingBuilder.cs b/src/IndentingBuilder/IndentingBuilder.cs
index 81b9215..821b871 100644
--- a/src/IndentingBuilder/IndentingBuilder.cs
+++ b/src/IndentingBuilder/IndentingBuilder.cs
@@ -37,7 +37,7 @@ namespace StaticCs
     /// Manages indentation levels with <see cref="Indent"/> and <see cref="Dedent"/> methods,
     /// and automatically applies the current indentation to appended content and interpolated strings.
     /// </summary>
-    public sealed class IndentingBuilder
+    internal sealed class IndentingBuilder
         : IComparable<IndentingBuilder>,
             IEquatable<IndentingBuilder>
     {
diff --git a/src/IndentingBuilder/IndentingBuilder.csproj b/src/IndentingBuilder/IndentingBuilder.csproj
index dcbbc8f..f037168 100644
--- a/src/IndentingBuilder/IndentingBuilder.csproj
+++ b/src/IndentingBuilder/IndentingBuilder.csproj
@@ -21,6 +21,13 @@
     <ContentTargetFolders>contentFiles</ContentTargetFolders>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="polysharp" Version="1.14.1">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+
   <ItemGroup>
     <None Include="IndentingBuilder.cs">
       <Pack>true</Pack>