diff --git a/test/Autofac.Test/Features/Decorators/DecoratorTests.cs b/test/Autofac.Test/Features/Decorators/DecoratorTests.cs
index 81fd4f4b2..be8b2046e 100644
--- a/test/Autofac.Test/Features/Decorators/DecoratorTests.cs
+++ b/test/Autofac.Test/Features/Decorators/DecoratorTests.cs
@@ -193,7 +193,10 @@ public void DecoratedRegistrationCanIncludeImplementationType()
         public void DecoratedRegistrationCanIncludeOtherServices()
         {
             var builder = new ContainerBuilder();
-            builder.RegisterType<ImplementorA>().As<IDecoratedService>().As<IService>();
+
+            // #963: The SingleInstance here is important - a single component may expose multiple services.
+            // If that component is decorated, the decorator ALSO needs to expose all of those services.
+            builder.RegisterType<ImplementorA>().As<IDecoratedService>().As<IService>().SingleInstance();
             builder.RegisterDecorator<DecoratorA, IDecoratedService>();
             var container = builder.Build();
 
diff --git a/test/Autofac.Test/Features/Decorators/OpenGenericDecoratorTests.cs b/test/Autofac.Test/Features/Decorators/OpenGenericDecoratorTests.cs
index bca06a1d1..78daf7a02 100644
--- a/test/Autofac.Test/Features/Decorators/OpenGenericDecoratorTests.cs
+++ b/test/Autofac.Test/Features/Decorators/OpenGenericDecoratorTests.cs
@@ -190,7 +190,10 @@ public void DecoratedRegistrationCanIncludeImplementationType()
         public void DecoratedRegistrationCanIncludeOtherServices()
         {
             var builder = new ContainerBuilder();
-            builder.RegisterGeneric(typeof(ImplementorA<>)).As(typeof(IDecoratedService<>)).As(typeof(IService<>));
+
+            // #963: The SingleInstance here is important - a single component may expose multiple services.
+            // If that component is decorated, the decorator ALSO needs to expose all of those services.
+            builder.RegisterGeneric(typeof(ImplementorA<>)).As(typeof(IDecoratedService<>)).As(typeof(IService<>)).SingleInstance();
             builder.RegisterGenericDecorator(typeof(DecoratorA<>), typeof(IDecoratedService<>));
             var container = builder.Build();