2 files changed, 4 insertions, 3 deletions
diff --git a/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs b/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
index f80935c..b081038 100644
--- a/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
+++ b/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
@@ -8,7 +8,6 @@ namespace DotNetOpenAuth.Test.OAuth.ChannelElements {
 	using System;
 	using System.Collections.Generic;
 	using System.Collections.Specialized;
-	using System.Diagnostics.Contracts;
 	using System.IO;
 	using System.Net;
 	using System.Text;
@@ -20,6 +19,7 @@ namespace DotNetOpenAuth.Test.OAuth.ChannelElements {
 	using DotNetOpenAuth.OAuth.ChannelElements;
 	using DotNetOpenAuth.Test.Mocks;
 	using NUnit.Framework;
+	using Validation;
 
 	[TestFixture]
 	public class OAuthChannelTests : TestBase {
diff --git a/src/DotNetOpenAuth.Test/OAuth/ChannelElements/SigningBindingElementBaseTests.cs b/src/DotNetOpenAuth.Test/OAuth/ChannelElements/SigningBindingElementBaseTests.cs
index dffe6c1..490399c 100644
--- a/src/DotNetOpenAuth.Test/OAuth/ChannelElements/SigningBindingElementBaseTests.cs
+++ b/src/DotNetOpenAuth.Test/OAuth/ChannelElements/SigningBindingElementBaseTests.cs
@@ -6,13 +6,13 @@
 
 namespace DotNetOpenAuth.Test.OAuth.ChannelElements {
 	using System.Collections.Generic;
-	using System.Diagnostics.Contracts;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.Messaging.Reflection;
 	using DotNetOpenAuth.OAuth;
 	using DotNetOpenAuth.OAuth.ChannelElements;
 	using DotNetOpenAuth.OAuth.Messages;
 	using NUnit.Framework;
+	using Validation;
 
 	[TestFixture]
 	public class SigningBindingElementBaseTests : MessagingTestBase {
@@ -125,7 +125,8 @@ namespace DotNetOpenAuth.Test.OAuth.ChannelElements {
 		}
 
 		internal AccessProtectedResourceRequest CreateResourceRequest(MessageReceivingEndpoint endpoint) {
-			Contract.Requires(endpoint != null);
+			Requires.NotNull(endpoint, "endpoint");
+
 			var message = new AccessProtectedResourceRequest(endpoint, Protocol.V10.Version);
 			return message;
 		}