1 files changed, 2 insertions, 2 deletions
diff --git a/src/DotNetOpenAuth.OAuth.ServiceProvider/OAuth/ChannelElements/OAuthServiceProviderChannel.cs b/src/DotNetOpenAuth.OAuth.ServiceProvider/OAuth/ChannelElements/OAuthServiceProviderChannel.cs
index 0d6450f..62019d8 100644
--- a/src/DotNetOpenAuth.OAuth.ServiceProvider/OAuth/ChannelElements/OAuthServiceProviderChannel.cs
+++ b/src/DotNetOpenAuth.OAuth.ServiceProvider/OAuth/ChannelElements/OAuthServiceProviderChannel.cs
@@ -8,11 +8,11 @@ namespace DotNetOpenAuth.OAuth.ChannelElements {
 	using System;
 	using System.Collections.Generic;
 	using System.Diagnostics.CodeAnalysis;
-	using System.Diagnostics.Contracts;
 	using System.Linq;
 	using System.Text;
 	using DotNetOpenAuth.Messaging;
 	using DotNetOpenAuth.Messaging.Bindings;
+	using Validation;
 
 	/// <summary>
 	/// The messaging channel for OAuth 1.0(a) Service Providers.
@@ -59,7 +59,7 @@ namespace DotNetOpenAuth.OAuth.ChannelElements {
 		/// An array of binding elements used to initialize the channel.
 		/// </returns>
 		private static IChannelBindingElement[] InitializeBindingElements(ITamperProtectionChannelBindingElement signingBindingElement, INonceStore store, ITokenManager tokenManager, SecuritySettings securitySettings) {
-			Contract.Requires(securitySettings != null);
+			Requires.NotNull(securitySettings, "securitySettings");
 
 			var bindingElements = OAuthChannel.InitializeBindingElements(signingBindingElement, store);