diff --git a/src/Microsoft.AspNet.Hosting/Program.cs b/src/Microsoft.AspNet.Hosting/Program.cs
index eb9e2eccbf..6004d8e50f 100644
--- a/src/Microsoft.AspNet.Hosting/Program.cs
+++ b/src/Microsoft.AspNet.Hosting/Program.cs
@@ -23,14 +23,16 @@ namespace Microsoft.AspNet.Hosting
         public void Main(string[] args)
         {
             // Allow the location of the ini file to be specfied via a --config command line arg
-            var tempConfig = new ConfigurationSection().AddCommandLine(args);
+            var tempBuilder = new ConfigurationBuilder().AddCommandLine(args);
+            var tempConfig = tempBuilder.Build();
             var configFilePath = tempConfig[ConfigFileKey] ?? HostingIniFile;
 
             var appBasePath = _serviceProvider.GetRequiredService<IApplicationEnvironment>().ApplicationBasePath;
-            var config = new ConfigurationSection(appBasePath);
-            config.AddIniFile(configFilePath, optional: true);
-            config.AddEnvironmentVariables();
-            config.AddCommandLine(args);
+            var builder = new ConfigurationBuilder(appBasePath);
+            builder.AddIniFile(configFilePath, optional: true);
+            builder.AddEnvironmentVariables();
+            builder.AddCommandLine(args);
+            var config = builder.Build();
 
             var host = new WebHostBuilder(_serviceProvider, config).Build();
             using (host.Start())
diff --git a/src/Microsoft.AspNet.Hosting/WebHostBuilder.cs b/src/Microsoft.AspNet.Hosting/WebHostBuilder.cs
index 7e204b3b96..4ae42e9c46 100644
--- a/src/Microsoft.AspNet.Hosting/WebHostBuilder.cs
+++ b/src/Microsoft.AspNet.Hosting/WebHostBuilder.cs
@@ -42,7 +42,8 @@ namespace Microsoft.AspNet.Hosting
         private string _serverFactoryLocation;
         private IServerFactory _serverFactory;
 
-        public WebHostBuilder([NotNull] IServiceProvider services) : this(services, config: new ConfigurationSection()) { }
+        public WebHostBuilder([NotNull] IServiceProvider services) 
+            : this(services, config: new ConfigurationBuilder().Build()) { }
 
         public WebHostBuilder([NotNull] IServiceProvider services, [NotNull] IConfiguration config)
         {
diff --git a/src/Microsoft.AspNet.TestHost/TestServer.cs b/src/Microsoft.AspNet.TestHost/TestServer.cs
index 4bc34a517c..3dfacf4b59 100644
--- a/src/Microsoft.AspNet.TestHost/TestServer.cs
+++ b/src/Microsoft.AspNet.TestHost/TestServer.cs
@@ -79,7 +79,7 @@ namespace Microsoft.AspNet.TestHost
         {
             return new WebHostBuilder(
                 services ?? CallContextServiceLocator.Locator.ServiceProvider,
-                config ?? new ConfigurationSection());
+                config ?? new ConfigurationBuilder().Build());
         }
 
         public static WebHostBuilder CreateBuilder()
diff --git a/test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs b/test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs
index 268a91a7d3..8c16801d1d 100644
--- a/test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs
+++ b/test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs
@@ -50,8 +50,9 @@ namespace Microsoft.AspNet.Hosting
                 { "server", "Microsoft.AspNet.Hosting.Tests" }
             };
 
-            var config = new ConfigurationSection()
+            var builder = new ConfigurationBuilder()
                 .Add(new MemoryConfigurationSource(vals));
+            var config = builder.Build();
             var host = CreateBuilder(config).Build();
             host.Start();
             Assert.NotNull(host.ApplicationServices.GetRequiredService<IHostingEnvironment>());
@@ -65,8 +66,9 @@ namespace Microsoft.AspNet.Hosting
                 { "Hosting:Server", "Microsoft.AspNet.Hosting.Tests" }
             };
 
-            var config = new ConfigurationSection()
+            var builder = new ConfigurationBuilder()
                 .Add(new MemoryConfigurationSource(vals));
+            var config = builder.Build();
             var host = CreateBuilder(config).Build();
             host.Start();
             Assert.NotNull(host.ApplicationServices.GetRequiredService<IHostingEnvironment>());
@@ -155,8 +157,9 @@ namespace Microsoft.AspNet.Hosting
                 { "ASPNET_ENV", "Staging" }
             };
 
-            var config = new ConfigurationSection()
+            var builder = new ConfigurationBuilder()
                 .Add(new MemoryConfigurationSource(vals));
+            var config = builder.Build();
 
             var engine = CreateBuilder(config).Build();
             var env = engine.ApplicationServices.GetRequiredService<IHostingEnvironment>();
@@ -171,8 +174,9 @@ namespace Microsoft.AspNet.Hosting
                 { "Hosting:Environment", "Staging" }
             };
 
-            var config = new ConfigurationSection()
+            var builder = new ConfigurationBuilder()
                 .Add(new MemoryConfigurationSource(vals));
+            var config = builder.Build();
 
             var engine = CreateBuilder(config).Build();
             var env = engine.ApplicationServices.GetRequiredService<IHostingEnvironment>();
@@ -382,7 +386,7 @@ namespace Microsoft.AspNet.Hosting
         {
             return new WebHostBuilder(
                 CallContextServiceLocator.Locator.ServiceProvider,
-                config ?? new ConfigurationSection());
+                config ?? new ConfigurationBuilder().Build());
         }
 
         public IServerInformation Initialize(IConfiguration configuration)
diff --git a/test/Microsoft.AspNet.TestHost.Tests/TestServerTests.cs b/test/Microsoft.AspNet.TestHost.Tests/TestServerTests.cs
index e65c0130e7..23ae59567b 100644
--- a/test/Microsoft.AspNet.TestHost.Tests/TestServerTests.cs
+++ b/test/Microsoft.AspNet.TestHost.Tests/TestServerTests.cs
@@ -37,7 +37,7 @@ namespace Microsoft.AspNet.TestHost
             Assert.Throws<InvalidOperationException>(
                 () => TestServer.Create(
                     services,
-                    new ConfigurationSection(), new Startup().Configure, configureServices: null));
+                    new ConfigurationBuilder().Build(), new Startup().Configure, configureServices: null));
         }
 
         [Fact]