diff --git a/src/Microsoft.AspNet.Hosting/PlatformHelper.cs b/src/Microsoft.AspNet.Hosting/PlatformHelper.cs
deleted file mode 100644
index fbe16751c1..0000000000
--- a/src/Microsoft.AspNet.Hosting/PlatformHelper.cs
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System;
-
-namespace Microsoft.AspNet.Hosting
-{
-    internal static class PlatformHelper
-    {
-        private static Lazy<bool> _isMono = new Lazy<bool>(() => Type.GetType("Mono.Runtime") != null);
-
-        public static bool IsMono
-        {
-            get
-            {
-                return _isMono.Value;
-            }
-        }
-    }
-}
\ No newline at end of file
diff --git a/src/Microsoft.AspNet.Hosting/Startup/ConfigureServicesDelegate.cs b/src/Microsoft.AspNet.Hosting/Startup/ConfigureServicesDelegate.cs
index 0935c7a69d..977cb07238 100644
--- a/src/Microsoft.AspNet.Hosting/Startup/ConfigureServicesDelegate.cs
+++ b/src/Microsoft.AspNet.Hosting/Startup/ConfigureServicesDelegate.cs
@@ -9,8 +9,6 @@ using Microsoft.Framework.Internal;
 
 namespace Microsoft.AspNet.Hosting.Startup
 {
-    public delegate IServiceProvider ConfigureServicesDelegate(IServiceCollection services);
-
     public class ConfigureServicesBuilder
     {
         public ConfigureServicesBuilder([NotNull] MethodInfo configureServices)
@@ -28,7 +26,7 @@ namespace Microsoft.AspNet.Hosting.Startup
 
         public MethodInfo MethodInfo { get; }
 
-        public ConfigureServicesDelegate Build(object instance) => services => Invoke(instance, services);
+        public Func<IServiceCollection, IServiceProvider> Build(object instance) => services => Invoke(instance, services);
 
         private IServiceProvider Invoke(object instance, [NotNull] IServiceCollection exportServices)
         {
diff --git a/src/Microsoft.AspNet.Hosting/Startup/StartupMethods.cs b/src/Microsoft.AspNet.Hosting/Startup/StartupMethods.cs
index c213a681d3..e8b61efdab 100644
--- a/src/Microsoft.AspNet.Hosting/Startup/StartupMethods.cs
+++ b/src/Microsoft.AspNet.Hosting/Startup/StartupMethods.cs
@@ -9,19 +9,20 @@ namespace Microsoft.AspNet.Hosting.Startup
 {
     public class StartupMethods
     {
-        internal static ConfigureServicesDelegate DefaultBuildServiceProvider = s => s.BuildServiceProvider();
+        internal static Func<IServiceCollection, IServiceProvider> DefaultBuildServiceProvider = s => s.BuildServiceProvider();
 
-        public StartupMethods(Action<IApplicationBuilder> configure) 
-            : this(configure, configureServices: null) { }
+        public StartupMethods(Action<IApplicationBuilder> configure)
+            : this(configure, configureServices: null)
+        {
+        }
 
-        // TODO: switch to ConfigureDelegate eventually
-        public StartupMethods(Action<IApplicationBuilder> configure, ConfigureServicesDelegate configureServices)
+        public StartupMethods(Action<IApplicationBuilder> configure, Func<IServiceCollection, IServiceProvider> configureServices)
         {
             ConfigureDelegate = configure;
             ConfigureServicesDelegate = configureServices ?? DefaultBuildServiceProvider;
         }
 
-        public ConfigureServicesDelegate ConfigureServicesDelegate { get; }
+        public Func<IServiceCollection, IServiceProvider> ConfigureServicesDelegate { get; }
         public Action<IApplicationBuilder> ConfigureDelegate { get; }
 
     }
diff --git a/src/Microsoft.AspNet.Hosting/WebHostBuilder.cs b/src/Microsoft.AspNet.Hosting/WebHostBuilder.cs
index 256f615597..06ae275e29 100644
--- a/src/Microsoft.AspNet.Hosting/WebHostBuilder.cs
+++ b/src/Microsoft.AspNet.Hosting/WebHostBuilder.cs
@@ -167,7 +167,7 @@ namespace Microsoft.AspNet.Hosting
             return UseStartup(configureApp, configureServices: null);
         }
 
-        public WebHostBuilder UseStartup([NotNull] Action<IApplicationBuilder> configureApp, ConfigureServicesDelegate configureServices)
+        public WebHostBuilder UseStartup([NotNull] Action<IApplicationBuilder> configureApp, Func<IServiceCollection, IServiceProvider> configureServices)
         {
             _startup = new StartupMethods(configureApp, configureServices);
             return this;