diff --git a/StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp10/OrderingRules/SA1210CSharp10CombinedSystemDirectivesUnitTests.cs b/StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp10/OrderingRules/SA1210CSharp10CombinedSystemDirectivesUnitTests.cs
index 58eab7583..bb3e6509c 100644
--- a/StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp10/OrderingRules/SA1210CSharp10CombinedSystemDirectivesUnitTests.cs
+++ b/StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp10/OrderingRules/SA1210CSharp10CombinedSystemDirectivesUnitTests.cs
@@ -3,9 +3,51 @@
 
 namespace StyleCop.Analyzers.Test.CSharp10.OrderingRules
 {
+    using System.Threading;
+    using System.Threading.Tasks;
     using StyleCop.Analyzers.Test.CSharp9.OrderingRules;
+    using Xunit;
+    using static StyleCop.Analyzers.Test.Verifiers.StyleCopCodeFixVerifier<
+        StyleCop.Analyzers.OrderingRules.SA1210UsingDirectivesMustBeOrderedAlphabeticallyByNamespace,
+        StyleCop.Analyzers.OrderingRules.UsingCodeFixProvider>;
 
     public class SA1210CSharp10CombinedSystemDirectivesUnitTests : SA1210CSharp9CombinedSystemDirectivesUnitTests
     {
+        [Fact]
+        public async Task TestUsingDirectivesInFileScopedNamespaceDeclarationAsync()
+        {
+            await new CSharpTest
+            {
+                TestSources =
+                {
+                    @"namespace Food;
+
+[|using System.Threading;|]
+using System;
+",
+                    @"namespace Bar;
+
+[|using Food;|]
+using Bar;
+[|using System.Threading;|]
+using System;
+",
+                },
+                FixedSources =
+                {
+                    @"namespace Food;
+using System;
+using System.Threading;
+",
+                    @"namespace Bar;
+using Bar;
+using Food;
+using System;
+using System.Threading;
+",
+                },
+                Settings = CombinedUsingDirectivesTestSettings,
+            }.RunAsync(CancellationToken.None).ConfigureAwait(false);
+        }
     }
 }
diff --git a/StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp10/OrderingRules/SA1210CSharp10UnitTests.cs b/StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp10/OrderingRules/SA1210CSharp10UnitTests.cs
index 84afe12e0..c9db20a85 100644
--- a/StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp10/OrderingRules/SA1210CSharp10UnitTests.cs
+++ b/StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp10/OrderingRules/SA1210CSharp10UnitTests.cs
@@ -3,9 +3,51 @@
 
 namespace StyleCop.Analyzers.Test.CSharp10.OrderingRules
 {
+    using System.Threading;
+    using System.Threading.Tasks;
+    using Microsoft.CodeAnalysis.Testing;
     using StyleCop.Analyzers.Test.CSharp9.OrderingRules;
+    using Xunit;
+    using static StyleCop.Analyzers.Test.Verifiers.StyleCopCodeFixVerifier<
+        StyleCop.Analyzers.OrderingRules.SA1210UsingDirectivesMustBeOrderedAlphabeticallyByNamespace,
+        StyleCop.Analyzers.OrderingRules.UsingCodeFixProvider>;
 
     public class SA1210CSharp10UnitTests : SA1210CSharp9UnitTests
     {
+        [Fact]
+        public async Task TestUsingDirectivesInFileScopedNamespaceDeclarationAsync()
+        {
+            await new CSharpTest
+            {
+                TestSources =
+                {
+                    @"namespace Foo;
+
+[|using System.Threading;|]
+using System;
+",
+                    @"namespace Bar;
+
+[|using Foo;|]
+using Bar;
+[|using System.Threading;|]
+using System;
+",
+                },
+                FixedSources =
+                {
+                    @"namespace Foo;
+using System;
+using System.Threading;
+",
+                    @"namespace Bar;
+using System;
+using System.Threading;
+using Bar;
+using Foo;
+",
+                },
+            }.RunAsync(CancellationToken.None).ConfigureAwait(false);
+        }
     }
 }
diff --git a/StyleCop.Analyzers/StyleCop.Analyzers.Test/OrderingRules/SA1210CombinedSystemDirectivesUnitTests.cs b/StyleCop.Analyzers/StyleCop.Analyzers.Test/OrderingRules/SA1210CombinedSystemDirectivesUnitTests.cs
index 29acbefdc..0f9d82008 100644
--- a/StyleCop.Analyzers/StyleCop.Analyzers.Test/OrderingRules/SA1210CombinedSystemDirectivesUnitTests.cs
+++ b/StyleCop.Analyzers/StyleCop.Analyzers.Test/OrderingRules/SA1210CombinedSystemDirectivesUnitTests.cs
@@ -18,6 +18,16 @@ namespace StyleCop.Analyzers.Test.OrderingRules
     /// </summary>
     public class SA1210CombinedSystemDirectivesUnitTests
     {
+        protected const string CombinedUsingDirectivesTestSettings = @"
+{
+  ""settings"": {
+    ""orderingRules"": {
+      ""systemUsingDirectivesFirst"": false
+    }
+  }
+}
+";
+
         [Fact]
         public async Task TestProperOrderedUsingDirectivesInNamespaceDeclarationAsync()
         {
@@ -212,16 +222,6 @@ private static Task VerifyCSharpDiagnosticAsync(string source, DiagnosticResult[
 
         private static Task VerifyCSharpFixAsync(string source, DiagnosticResult[] expected, string fixedSource, CancellationToken cancellationToken)
         {
-            const string CombinedUsingDirectivesTestSettings = @"
-{
-  ""settings"": {
-    ""orderingRules"": {
-      ""systemUsingDirectivesFirst"": false
-    }
-  }
-}
-";
-
             var test = new StyleCopCodeFixVerifier<SA1210UsingDirectivesMustBeOrderedAlphabeticallyByNamespace, UsingCodeFixProvider>.CSharpTest
             {
                 TestCode = source,
diff --git a/StyleCop.Analyzers/StyleCop.Analyzers/OrderingRules/SA1210UsingDirectivesMustBeOrderedAlphabeticallyByNamespace.cs b/StyleCop.Analyzers/StyleCop.Analyzers/OrderingRules/SA1210UsingDirectivesMustBeOrderedAlphabeticallyByNamespace.cs
index 99424ebc2..1fad7c2f5 100644
--- a/StyleCop.Analyzers/StyleCop.Analyzers/OrderingRules/SA1210UsingDirectivesMustBeOrderedAlphabeticallyByNamespace.cs
+++ b/StyleCop.Analyzers/StyleCop.Analyzers/OrderingRules/SA1210UsingDirectivesMustBeOrderedAlphabeticallyByNamespace.cs
@@ -11,6 +11,7 @@ namespace StyleCop.Analyzers.OrderingRules
     using Microsoft.CodeAnalysis.CSharp.Syntax;
     using Microsoft.CodeAnalysis.Diagnostics;
     using StyleCop.Analyzers.Helpers;
+    using StyleCop.Analyzers.Lightup;
     using StyleCop.Analyzers.Settings.ObjectModel;
 
     /// <summary>
@@ -40,7 +41,7 @@ internal class SA1210UsingDirectivesMustBeOrderedAlphabeticallyByNamespace : Dia
             new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat, AnalyzerCategory.OrderingRules, DiagnosticSeverity.Warning, AnalyzerConstants.EnabledByDefault, Description, HelpLink);
 
         private static readonly Action<SyntaxNodeAnalysisContext, StyleCopSettings> CompilationUnitAction = HandleCompilationUnit;
-        private static readonly Action<SyntaxNodeAnalysisContext, StyleCopSettings> NamespaceDeclarationAction = HandleNamespaceDeclaration;
+        private static readonly Action<SyntaxNodeAnalysisContext, StyleCopSettings> BaseNamespaceDeclarationAction = HandleBaseNamespaceDeclaration;
 
         /// <inheritdoc/>
         public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } =
@@ -53,7 +54,7 @@ public override void Initialize(AnalysisContext context)
             context.EnableConcurrentExecution();
 
             context.RegisterSyntaxNodeAction(CompilationUnitAction, SyntaxKind.CompilationUnit);
-            context.RegisterSyntaxNodeAction(NamespaceDeclarationAction, SyntaxKind.NamespaceDeclaration);
+            context.RegisterSyntaxNodeAction(BaseNamespaceDeclarationAction, SyntaxKinds.BaseNamespaceDeclaration);
         }
 
         private static void HandleCompilationUnit(SyntaxNodeAnalysisContext context, StyleCopSettings settings)
@@ -63,9 +64,9 @@ private static void HandleCompilationUnit(SyntaxNodeAnalysisContext context, Sty
             ProcessUsings(context, settings.OrderingRules, compilationUnit.Usings);
         }
 
-        private static void HandleNamespaceDeclaration(SyntaxNodeAnalysisContext context, StyleCopSettings settings)
+        private static void HandleBaseNamespaceDeclaration(SyntaxNodeAnalysisContext context, StyleCopSettings settings)
         {
-            var namespaceDeclaration = (NamespaceDeclarationSyntax)context.Node;
+            var namespaceDeclaration = (BaseNamespaceDeclarationSyntaxWrapper)context.Node;
 
             ProcessUsings(context, settings.OrderingRules, namespaceDeclaration.Usings);
         }