diff --git a/jwl.test/WadlTests.cs b/jwl.test/WadlTests.cs
index b3a8228..4cb7f1f 100644
--- a/jwl.test/WadlTests.cs
+++ b/jwl.test/WadlTests.cs
@@ -7,7 +7,7 @@ public class WadlTests
     : IDisposable
 {
     private readonly XmlSerializer _wadlSerializer;
-    private Stream _wadlResponseStream;
+    private readonly Stream _wadlResponseStream;
 
     public WadlTests()
     {