diff --git a/src/Client/Core/DependencyInjection/ServiceCollectionExtensions.cs b/src/Client/Core/DependencyInjection/ServiceCollectionExtensions.cs
index 89d4db19..a1d96c5f 100644
--- a/src/Client/Core/DependencyInjection/ServiceCollectionExtensions.cs
+++ b/src/Client/Core/DependencyInjection/ServiceCollectionExtensions.cs
@@ -13,14 +13,15 @@ namespace Microsoft.DurableTask.Client;
 public static class ServiceCollectionExtensions
 {
     /// <summary>
-    /// Adds and configures Durable Task worker services to the service collection.
+    /// Configures and adds a <see cref="DurableTaskClient" /> to the service collection.
     /// </summary>
     /// <param name="services">The service collection to add to.</param>
     /// <param name="name">The name of the builder to add.</param>
     /// <returns>The builder used to configured the <see cref="DurableTaskClient"/>.</returns>
     public static IDurableTaskClientBuilder AddDurableTaskClient(this IServiceCollection services, string? name = null)
     {
-        Check.NotNull(services);
+        Check.NotNull(services);
+        services.TryAddSingleton<IDurableTaskClientProvider, DefaultDurableTaskClientProvider>();
         IDurableTaskClientBuilder builder = GetBuilder(services, name ?? Options.DefaultName, out bool added);
         ConditionalConfigureBuilder(services, builder, added);
         return builder;
@@ -47,7 +48,8 @@ public static IServiceCollection AddDurableTaskClient(
     /// <returns>The original service collection, for call chaining.</returns>
     public static IServiceCollection AddDurableTaskClient(
         this IServiceCollection services, string name, Action<IDurableTaskClientBuilder> configure)
-    {
+    {
+        Check.NotNull(services);
         services.TryAddSingleton<IDurableTaskClientProvider, DefaultDurableTaskClientProvider>();
         IDurableTaskClientBuilder builder = GetBuilder(services, name, out bool added);
         configure.Invoke(builder);
diff --git a/test/Client/Core.Tests/DependencyInjection/ServiceCollectionExtensionsTests.cs b/test/Client/Core.Tests/DependencyInjection/ServiceCollectionExtensionsTests.cs
index 7ddce4d5..2dd643ac 100644
--- a/test/Client/Core.Tests/DependencyInjection/ServiceCollectionExtensionsTests.cs
+++ b/test/Client/Core.Tests/DependencyInjection/ServiceCollectionExtensionsTests.cs
@@ -121,6 +121,17 @@ public void AddDurableTaskClient_Named_HostedServiceAdded()
             x => x.ServiceType == typeof(IDurableTaskClientProvider) && x.Lifetime == ServiceLifetime.Singleton);
         services.Should().NotContain(
             x => x.ServiceType == typeof(DurableTaskClient) && x.Lifetime == ServiceLifetime.Singleton);
+    }
+
+    [Fact]
+    public void AddDurableTaskClient_Unnamed_HostedServiceAdded()
+    {
+        ServiceCollection services = new();
+        services.AddDurableTaskClient();
+        services.Should().ContainSingle(
+            x => x.ServiceType == typeof(IDurableTaskClientProvider) && x.Lifetime == ServiceLifetime.Singleton);
+        services.Should().ContainSingle(
+            x => x.ServiceType == typeof(DurableTaskClient) && x.Lifetime == ServiceLifetime.Singleton);
     }
 
     [Fact]
@@ -145,6 +156,19 @@ public void AddDurableTaskClient_DoesNotConfiguresConverter()
 
         DurableTaskClientOptions options = services.BuildServiceProvider().GetOptions<DurableTaskClientOptions>();
         options.DataConverter.Should().BeSameAs(JsonDataConverter.Default);
+    }
+
+    [Fact]
+    public void AddDurableTaskClient_NullServices_ThrowsException()
+    {
+        Action act = () => ((ServiceCollection)null!).AddDurableTaskClient();
+        act.Should().Throw<ArgumentNullException>();
+
+        act = () => ((ServiceCollection)null!).AddDurableTaskClient(builder => { });
+        act.Should().Throw<ArgumentNullException>();
+
+        act = () => ((ServiceCollection)null!).AddDurableTaskClient("name", builder => { });
+        act.Should().Throw<ArgumentNullException>();
     }
 
     class CustomDataConverter : DataConverter