diff --git a/test/unit/Elsa.Activities.UnitTests/Helpers/ActivityTestHelper.cs b/test/unit/Elsa.Activities.UnitTests/Helpers/ActivityTestHelper.cs
index 1a2adedb4..68d47361e 100644
--- a/test/unit/Elsa.Activities.UnitTests/Helpers/ActivityTestHelper.cs
+++ b/test/unit/Elsa.Activities.UnitTests/Helpers/ActivityTestHelper.cs
@@ -59,7 +59,6 @@ public static class ActivityTestHelper
         services.AddSingleton<IActivityDescriber, ActivityDescriber>();
         services.AddSingleton<IPropertyDefaultValueResolver, PropertyDefaultValueResolver>();
         services.AddSingleton<IActivityFactory, ActivityFactory>();
-        services.AddSingleton<IPropertyDefaultValueResolver, PropertyDefaultValueResolver>();
         services.AddSingleton<IPropertyUIHandlerResolver, PropertyUIHandlerResolver>();
         services.AddSingleton<IActivityRegistry, ActivityRegistry>();
         services.AddScoped<IActivityRegistryLookupService, ActivityRegistryLookupService>();