diff --git a/src/Aspire.Hosting/Health/ResourceHealthCheckScheduler.cs b/src/Aspire.Hosting/Health/ResourceHealthCheckScheduler.cs
index 89823798a63..6a6b28f8dff 100644
--- a/src/Aspire.Hosting/Health/ResourceHealthCheckScheduler.cs
+++ b/src/Aspire.Hosting/Health/ResourceHealthCheckScheduler.cs
@@ -13,7 +13,7 @@ internal class ResourceHealthCheckScheduler : BackgroundService
     private readonly ResourceNotificationService _resourceNotificationService;
     private readonly DistributedApplicationModel _model;
     private readonly Dictionary<string, bool> _checkEnablement = new();
-    private readonly List<string> _healthyResources = new();
+    private readonly HashSet<string> _healthyResources = new();
 
     public ResourceHealthCheckScheduler(ResourceNotificationService resourceNotificationService, DistributedApplicationModel model, IDistributedApplicationEventing eventing)
     {
diff --git a/src/Aspire.Hosting/Health/ResourceNotificationHealthCheckPublisher.cs b/src/Aspire.Hosting/Health/ResourceNotificationHealthCheckPublisher.cs
index 6ac43ab79df..bb3ad6fc209 100644
--- a/src/Aspire.Hosting/Health/ResourceNotificationHealthCheckPublisher.cs
+++ b/src/Aspire.Hosting/Health/ResourceNotificationHealthCheckPublisher.cs
@@ -9,7 +9,7 @@ namespace Aspire.Hosting.Health;
 
 internal class ResourceNotificationHealthCheckPublisher(DistributedApplicationModel model, ResourceNotificationService resourceNotificationService, IDistributedApplicationEventing eventing, IServiceProvider services) : IHealthCheckPublisher
 {
-    private readonly List<string> _alreadyHealthy = new();
+    private readonly HashSet<string> _alreadyHealthy = new();
 
     public async Task PublishAsync(HealthReport report, CancellationToken cancellationToken)
     {