diff --git a/src/Mvc/Mvc.ApiExplorer/src/EndpointMetadataApiDescriptionProvider.cs b/src/Mvc/Mvc.ApiExplorer/src/EndpointMetadataApiDescriptionProvider.cs
index 2f25045d3787..6ac98b069fb2 100644
--- a/src/Mvc/Mvc.ApiExplorer/src/EndpointMetadataApiDescriptionProvider.cs
+++ b/src/Mvc/Mvc.ApiExplorer/src/EndpointMetadataApiDescriptionProvider.cs
@@ -274,7 +274,7 @@ private static ParameterDescriptor CreateParameterDescriptor(ParameterInfo param
         {
             return (BindingSource.FormFile, fromFormAttribute.Name ?? parameter.Name ?? string.Empty, false, parameterType);
         }
-        else if (parameter.ParameterInfo.CustomAttributes.Any(a => typeof(IFromServiceMetadata).IsAssignableFrom(a.AttributeType) || typeof(FromKeyedServicesAttribute) == a.AttributeType) ||
+        else if (parameter.ParameterInfo.CustomAttributes.Any(a => a.AttributeType.IsAssignableTo(typeof(IFromServiceMetadata)) || a.AttributeType.IsAssignableTo(typeof(FromKeyedServicesAttribute))) ||
                  parameterType == typeof(HttpContext) ||
                  parameterType == typeof(HttpRequest) ||
                  parameterType == typeof(HttpResponse) ||
diff --git a/src/Mvc/Mvc.ApiExplorer/test/EndpointMetadataApiDescriptionProviderTest.cs b/src/Mvc/Mvc.ApiExplorer/test/EndpointMetadataApiDescriptionProviderTest.cs
index 7de4d5eb5b89..736de8edf95f 100644
--- a/src/Mvc/Mvc.ApiExplorer/test/EndpointMetadataApiDescriptionProviderTest.cs
+++ b/src/Mvc/Mvc.ApiExplorer/test/EndpointMetadataApiDescriptionProviderTest.cs
@@ -796,6 +796,7 @@ public void DoesNotAddFromServiceParameterAsService()
         Assert.Empty(GetApiDescription((IInferredServiceInterface foo) => { }).ParameterDescriptions);
         Assert.Empty(GetApiDescription(([FromServices] InferredServiceClass foo) => { }).ParameterDescriptions);
         Assert.Empty(GetApiDescription(([FromKeyedServices("foo")] InferredServiceClass foo) => { }).ParameterDescriptions);
+        Assert.Empty(GetApiDescription(([CustomFromKeyedServices("foo")] InferredServiceClass foo) => { }).ParameterDescriptions);
         Assert.Empty(GetApiDescription((HttpContext context) => { }).ParameterDescriptions);
         Assert.Empty(GetApiDescription((HttpRequest request) => { }).ParameterDescriptions);
         Assert.Empty(GetApiDescription((HttpResponse response) => { }).ParameterDescriptions);
@@ -1814,6 +1815,10 @@ private class InferredServiceClass : IInferredServiceInterface
     {
     }
 
+    private class CustomFromKeyedServicesAttribute(string key) : FromKeyedServicesAttribute("Custom" + key)
+    {
+    }
+
     private class ServiceProviderIsService : IServiceProviderIsService
     {
         public bool IsService(Type serviceType) => serviceType == typeof(IInferredServiceInterface);
diff --git a/src/OpenApi/src/Services/OpenApiGenerator.cs b/src/OpenApi/src/Services/OpenApiGenerator.cs
index fd56a779dc88..a0c2118eac4a 100644
--- a/src/OpenApi/src/Services/OpenApiGenerator.cs
+++ b/src/OpenApi/src/Services/OpenApiGenerator.cs
@@ -424,7 +424,7 @@ private List<IOpenApiParameter> GetOpenApiParameters(MethodInfo methodInfo, Rout
         {
             return (true, null, null);
         }
-        else if (parameter.CustomAttributes.Any(a => typeof(IFromServiceMetadata).IsAssignableFrom(a.AttributeType) || typeof(FromKeyedServicesAttribute) == a.AttributeType) ||
+        else if (parameter.CustomAttributes.Any(a => a.AttributeType.IsAssignableTo(typeof(IFromServiceMetadata)) || a.AttributeType.IsAssignableTo(typeof(FromKeyedServicesAttribute))) ||
                 parameter.ParameterType == typeof(HttpContext) ||
                 parameter.ParameterType == typeof(HttpRequest) ||
                 parameter.ParameterType == typeof(HttpResponse) ||
diff --git a/src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiGeneratorTests.cs b/src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiGeneratorTests.cs
index 3dbf13d3995f..72de97aa9b9d 100644
--- a/src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiGeneratorTests.cs
+++ b/src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiGeneratorTests.cs
@@ -414,6 +414,7 @@ public void DoesNotAddFromServiceParameterAsService()
         Assert.Empty(GetOpenApiOperation((IInferredServiceInterface foo) => { }).Parameters);
         Assert.Empty(GetOpenApiOperation(([FromServices] int foo) => { }).Parameters);
         Assert.Empty(GetOpenApiOperation(([FromKeyedServices("foo")] int foo) => { }).Parameters);
+        Assert.Empty(GetOpenApiOperation(([CustomFromKeyedServices("foo")] int foo) => { }).Parameters);
         Assert.Empty(GetOpenApiOperation((HttpContext context) => { }).Parameters);
         Assert.Empty(GetOpenApiOperation((HttpRequest request) => { }).Parameters);
         Assert.Empty(GetOpenApiOperation((HttpResponse response) => { }).Parameters);
@@ -1086,6 +1087,10 @@ private interface IInferredServiceInterface
     {
     }
 
+    private class CustomFromKeyedServicesAttribute(string key) : FromKeyedServicesAttribute("Custom" + key)
+    {
+    }
+
     private record BindAsyncRecord(int Value)
     {
         public static ValueTask<BindAsyncRecord> BindAsync(HttpContext context, ParameterInfo parameter) =>