1 files changed, 3 insertions, 2 deletions
diff --git a/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs b/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
index 856f164..809fae7 100644
--- a/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
+++ b/src/DotNetOpenAuth.Test/OAuth/ChannelElements/OAuthChannelTests.cs
@@ -8,6 +8,7 @@ namespace DotNetOpenAuth.Test.ChannelElements {
 	using System;
 	using System.Collections.Generic;
 	using System.Collections.Specialized;
+	using System.Diagnostics.Contracts;
 	using System.IO;
 	using System.Net;
 	using System.Text;
@@ -40,7 +41,7 @@ namespace DotNetOpenAuth.Test.ChannelElements {
 			this.channel.WebRequestHandler = this.webRequestHandler;
 		}
 
-		[TestMethod, ExpectedException(typeof(ArgumentException))]
+		[TestMethod, ExpectedException(typeof(ArgumentNullException))]
 		public void CtorNullSigner() {
 			new OAuthChannel(null, this.nonceStore, new InMemoryTokenManager(), new TestMessageFactory());
 		}
@@ -243,7 +244,7 @@ namespace DotNetOpenAuth.Test.ChannelElements {
 		}
 
 		private static string CreateAuthorizationHeader(IDictionary<string, string> fields) {
-			ErrorUtilities.VerifyArgumentNotNull(fields, "fields");
+			Contract.Requires<ArgumentNullException>(fields != null);
 
 			StringBuilder authorization = new StringBuilder();
 			authorization.Append("OAuth ");