diff --git a/src/Microsoft.ML.Tokenizers/Utils/DoubleArrayTrie.cs b/src/Microsoft.ML.Tokenizers/Utils/DoubleArrayTrie.cs
index 8e1fafbd74..f0465e315d 100644
--- a/src/Microsoft.ML.Tokenizers/Utils/DoubleArrayTrie.cs
+++ b/src/Microsoft.ML.Tokenizers/Utils/DoubleArrayTrie.cs
@@ -20,7 +20,7 @@ namespace Microsoft.ML.Tokenizers
     //
     // Succinct bit vector.
     //
-    public class BitVector
+    internal class BitVector
     {
         private const int UnitSize = sizeof(uint) * 8;
         private readonly List<uint> _units = new();
@@ -279,7 +279,7 @@ internal struct DawgUnit
     // Directed Acyclic Word Graph (DAWG) builder.
     //
 
-    public class DawgBuilder
+    internal class DawgBuilder
     {
         private const int InitialTableSize = 1 << 10;