diff --git a/dotnet/src/webdriver/Internal/Base64UrlEncoder.cs b/dotnet/src/webdriver/Internal/Base64UrlEncoder.cs
index c8b22e7223e8b..6c76ab9ae93db 100644
--- a/dotnet/src/webdriver/Internal/Base64UrlEncoder.cs
+++ b/dotnet/src/webdriver/Internal/Base64UrlEncoder.cs
@@ -18,6 +18,7 @@
 // </copyright>
 
 using System;
+using System.ComponentModel;
 
 #nullable enable
 
@@ -33,6 +34,7 @@ namespace OpenQA.Selenium.Internal
     /// <summary>
     /// Encodes and Decodes strings as Base64Url encoding.
     /// </summary>
+    [EditorBrowsable(EditorBrowsableState.Never)]
     public static class Base64UrlEncoder
     {
         private const char base64PadCharacter = '=';
diff --git a/dotnet/src/webdriver/Internal/PortUtilities.cs b/dotnet/src/webdriver/Internal/PortUtilities.cs
index 26c45a8b2688f..866087ba08834 100644
--- a/dotnet/src/webdriver/Internal/PortUtilities.cs
+++ b/dotnet/src/webdriver/Internal/PortUtilities.cs
@@ -17,14 +17,18 @@
 // under the License.
 // </copyright>
 
+using System.ComponentModel;
 using System.Net;
 using System.Net.Sockets;
 
+#nullable enable
+
 namespace OpenQA.Selenium.Internal
 {
     /// <summary>
     /// Encapsulates methods for working with ports.
     /// </summary>
+    [EditorBrowsable(EditorBrowsableState.Never)]
     public static class PortUtilities
     {
         /// <summary>
@@ -42,7 +46,7 @@ public static int FindFreePort()
             {
                 IPEndPoint socketEndPoint = new IPEndPoint(IPAddress.Any, 0);
                 portSocket.Bind(socketEndPoint);
-                socketEndPoint = (IPEndPoint)portSocket.LocalEndPoint;
+                socketEndPoint = (IPEndPoint)portSocket.LocalEndPoint!;
                 listeningPort = socketEndPoint.Port;
             }
             finally
diff --git a/dotnet/src/webdriver/Internal/ReturnedCookie.cs b/dotnet/src/webdriver/Internal/ReturnedCookie.cs
index bef50faa49662..340210667e3c1 100644
--- a/dotnet/src/webdriver/Internal/ReturnedCookie.cs
+++ b/dotnet/src/webdriver/Internal/ReturnedCookie.cs
@@ -18,6 +18,7 @@
 // </copyright>
 
 using System;
+using System.ComponentModel;
 using System.Globalization;
 
 namespace OpenQA.Selenium.Internal
@@ -25,6 +26,7 @@ namespace OpenQA.Selenium.Internal
     /// <summary>
     /// Represents a cookie returned to the driver by the browser.
     /// </summary>
+    [EditorBrowsable(EditorBrowsableState.Never)]
     public class ReturnedCookie : Cookie
     {