diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
index 8d3d62bb9c8734..7bdf2d6a102ea4 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
@@ -46,7 +46,7 @@ public NotFoundFileInfo(string name) { }
         [System.Diagnostics.CodeAnalysis.DoesNotReturn]
         public System.IO.Stream CreateReadStream() { throw null; }
     }
-    public partial class NullChangeToken : Microsoft.Extensions.Primitives.IChangeToken
+    public sealed partial class NullChangeToken : Microsoft.Extensions.Primitives.IChangeToken
     {
         internal NullChangeToken() { }
         public bool ActiveChangeCallbacks { get { throw null; } }
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullChangeToken.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullChangeToken.cs
index 17812a299490ee..eb10eed91052a2 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullChangeToken.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullChangeToken.cs
@@ -9,7 +9,7 @@ namespace Microsoft.Extensions.FileProviders
     /// <summary>
     /// An empty change token that doesn't raise any change callbacks.
     /// </summary>
-    public class NullChangeToken : IChangeToken
+    public sealed class NullChangeToken : IChangeToken
     {
         /// <summary>
         /// Gets a singleton instance of <see cref="NullChangeToken"/>.
diff --git a/src/libraries/Microsoft.Extensions.Logging.Abstractions/ref/Microsoft.Extensions.Logging.Abstractions.cs b/src/libraries/Microsoft.Extensions.Logging.Abstractions/ref/Microsoft.Extensions.Logging.Abstractions.cs
index cd1125477953f3..34f8935ac470cd 100644
--- a/src/libraries/Microsoft.Extensions.Logging.Abstractions/ref/Microsoft.Extensions.Logging.Abstractions.cs
+++ b/src/libraries/Microsoft.Extensions.Logging.Abstractions/ref/Microsoft.Extensions.Logging.Abstractions.cs
@@ -193,7 +193,7 @@ public void AddProvider(Microsoft.Extensions.Logging.ILoggerProvider provider) {
         public Microsoft.Extensions.Logging.ILogger CreateLogger(string name) { throw null; }
         public void Dispose() { }
     }
-    public partial class NullLoggerProvider : Microsoft.Extensions.Logging.ILoggerProvider, System.IDisposable
+    public sealed partial class NullLoggerProvider : Microsoft.Extensions.Logging.ILoggerProvider, System.IDisposable
     {
         internal NullLoggerProvider() { }
         public static Microsoft.Extensions.Logging.Abstractions.NullLoggerProvider Instance { get { throw null; } }
diff --git a/src/libraries/Microsoft.Extensions.Logging.Abstractions/src/NullLoggerProvider.cs b/src/libraries/Microsoft.Extensions.Logging.Abstractions/src/NullLoggerProvider.cs
index 98c8624297100c..1ca696ef2a6430 100644
--- a/src/libraries/Microsoft.Extensions.Logging.Abstractions/src/NullLoggerProvider.cs
+++ b/src/libraries/Microsoft.Extensions.Logging.Abstractions/src/NullLoggerProvider.cs
@@ -6,7 +6,7 @@ namespace Microsoft.Extensions.Logging.Abstractions
     /// <summary>
     /// Provider for the <see cref="NullLogger"/>.
     /// </summary>
-    public class NullLoggerProvider : ILoggerProvider
+    public sealed class NullLoggerProvider : ILoggerProvider
     {
         /// <summary>
         /// Returns an instance of <see cref="NullLoggerProvider"/>.