diff --git a/csharp/src/Google.Protobuf/ByteString.cs b/csharp/src/Google.Protobuf/ByteString.cs
index b948f2da3e2e..4d75ff9dfa88 100644
--- a/csharp/src/Google.Protobuf/ByteString.cs
+++ b/csharp/src/Google.Protobuf/ByteString.cs
@@ -57,14 +57,6 @@ public sealed class ByteString : IEnumerable<byte>, IEquatable<ByteString>
 
         private readonly ReadOnlyMemory<byte> bytes;
 
-        /// <summary>
-        /// Internal use only.  Ensure that the provided array is not mutated and belongs to this instance.
-        /// </summary>
-        internal static ByteString AttachBytes(byte[] bytes)
-        {
-            return new ByteString(bytes);
-        }
-
         /// <summary>
         /// Internal use only.  Ensure that the provided array is not mutated and belongs to this instance.
         /// </summary>