diff --git a/src/Parlot/CharMap.cs b/src/Parlot/CharMap.cs
index 8c14c2a..5ceb6ee 100644
--- a/src/Parlot/CharMap.cs
+++ b/src/Parlot/CharMap.cs
@@ -5,7 +5,7 @@
 
 namespace Parlot;
 
-public sealed class CharMap<T> where T : class
+internal sealed class CharMap<T> where T : class
 {
     private readonly T[] _asciiMap = new T[128];
     private Dictionary<uint, T>? _nonAsciiMap;