diff --git a/src/Framework/AspNetCoreAnalyzers/src/Analyzers/RouteHandlers/DisallowNonParsableComplexTypesOnParameters.cs b/src/Framework/AspNetCoreAnalyzers/src/Analyzers/RouteHandlers/DisallowNonParsableComplexTypesOnParameters.cs
index 22ef6d3bdd38..3415579ff0aa 100644
--- a/src/Framework/AspNetCoreAnalyzers/src/Analyzers/RouteHandlers/DisallowNonParsableComplexTypesOnParameters.cs
+++ b/src/Framework/AspNetCoreAnalyzers/src/Analyzers/RouteHandlers/DisallowNonParsableComplexTypesOnParameters.cs
@@ -129,7 +129,7 @@ static bool ReportFromAttributeDiagnostic(OperationAnalysisContext context, Well
 
             // If it is nullable and we have type arguments, unwrap it.
             // The length check aims to alleviate AD0001 warnings when referencing methods in external class libraries that contain parameters
-            if (parameterTypeSymbol!.ConstructedFrom.SpecialType == SpecialType.System_Nullable_T &&
+            if (parameterTypeSymbol?.ConstructedFrom.SpecialType == SpecialType.System_Nullable_T &&
                 parameterTypeSymbol.TypeArguments.Length > 0)
             {
                 parameterTypeSymbol = parameterTypeSymbol.TypeArguments[0] as INamedTypeSymbol;
diff --git a/src/Framework/AspNetCoreAnalyzers/test/RouteHandlers/DisallowNonParsableComplexTypesOnParametersTest.cs b/src/Framework/AspNetCoreAnalyzers/test/RouteHandlers/DisallowNonParsableComplexTypesOnParametersTest.cs
index 58e7476ca796..819eea5fd2da 100644
--- a/src/Framework/AspNetCoreAnalyzers/test/RouteHandlers/DisallowNonParsableComplexTypesOnParametersTest.cs
+++ b/src/Framework/AspNetCoreAnalyzers/test/RouteHandlers/DisallowNonParsableComplexTypesOnParametersTest.cs
@@ -738,5 +738,28 @@ public class CommercialCustomer : ICustomer
         // Act
         await VerifyCS.VerifyAnalyzerAsync(source);
     }
+
+    [Fact]
+    public async Task Handler_Parameter_WithGenericTypeParameter_Works()
+    {
+        // Arrange
+        var source = """
+            using Microsoft.AspNetCore.Builder;
+
+            var webApp = WebApplication.Create();
+
+            static void UseEndpoint<TEndpointInput>(WebApplication app) where TEndpointInput : class
+            {
+                app.MapPost("/test", (TEndpointInput data) => { });
+            }
+
+            UseEndpoint<TestEndpointInput>(webApp);
+
+            public class TestEndpointInput { }
+            """;
+
+        // Act
+        await VerifyCS.VerifyAnalyzerAsync(source);
+    }
 }
 
diff --git a/src/Framework/AspNetCoreAnalyzers/test/Verifiers/CSharpAnalyzerVerifier.cs b/src/Framework/AspNetCoreAnalyzers/test/Verifiers/CSharpAnalyzerVerifier.cs
index cfbc023573b3..d146f8b471be 100644
--- a/src/Framework/AspNetCoreAnalyzers/test/Verifiers/CSharpAnalyzerVerifier.cs
+++ b/src/Framework/AspNetCoreAnalyzers/test/Verifiers/CSharpAnalyzerVerifier.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.InternalTesting;
@@ -30,7 +31,7 @@ public static DiagnosticResult Diagnostic(DiagnosticDescriptor descriptor)
         => CSharpAnalyzerVerifier<TAnalyzer, DefaultVerifier>.Diagnostic(descriptor);
 
     /// <inheritdoc cref="AnalyzerVerifier{TAnalyzer, TTest, TVerifier}.VerifyAnalyzerAsync(string, DiagnosticResult[])"/>
-    public static async Task VerifyAnalyzerAsync(string source, params DiagnosticResult[] expected)
+    public static async Task VerifyAnalyzerAsync([StringSyntax("C#-test")] string source, params DiagnosticResult[] expected)
     {
         var test = new CSharpAnalyzerTest<TAnalyzer, DefaultVerifier>
         {