1 files changed, 2 insertions, 3 deletions
diff --git a/src/DotNetOpenAuth.Core/Configuration/HostNameOrRegexCollection.cs b/src/DotNetOpenAuth.Core/Configuration/HostNameOrRegexCollection.cs
index f009ce5..8f537c3 100644
--- a/src/DotNetOpenAuth.Core/Configuration/HostNameOrRegexCollection.cs
+++ b/src/DotNetOpenAuth.Core/Configuration/HostNameOrRegexCollection.cs
@@ -7,13 +7,12 @@
 namespace DotNetOpenAuth.Configuration {
 	using System.Collections.Generic;
 	using System.Configuration;
-	using System.Diagnostics.Contracts;
 	using System.Text.RegularExpressions;
+	using Validation;
 
 	/// <summary>
 	/// Represents a collection of child elements that describe host names either as literal host names or regex patterns.
 	/// </summary>
-	[ContractVerification(true)]
 	internal class HostNameOrRegexCollection : ConfigurationElementCollection {
 		/// <summary>
 		/// Initializes a new instance of the <see cref="HostNameOrRegexCollection"/> class.
@@ -63,7 +62,7 @@ namespace DotNetOpenAuth.Configuration {
 		/// An <see cref="T:System.Object"/> that acts as the key for the specified <see cref="T:System.Configuration.ConfigurationElement"/>.
 		/// </returns>
 		protected override object GetElementKey(ConfigurationElement element) {
-			Contract.Assume(element != null); // this should be Contract.Requires in base class.
+			Requires.NotNull(element, "element");
 			return ((HostNameElement)element).Name ?? string.Empty;
 		}
 	}