diff --git a/websocket-sharp/Net/HttpListener.cs b/websocket-sharp/Net/HttpListener.cs
index c40fa376..f46729e5 100644
--- a/websocket-sharp/Net/HttpListener.cs
+++ b/websocket-sharp/Net/HttpListener.cs
@@ -454,13 +454,21 @@ namespace WebSocketSharp.Net
     }
 
     /// <summary>
-    /// Gets or sets the delegate called to find the credentials for an identity used to
-    /// authenticate a client.
+    /// Gets or sets the delegate called to find the credentials for
+    /// an identity used to authenticate a client.
     /// </summary>
     /// <value>
-    /// A <c>Func&lt;<see cref="IIdentity"/>, <see cref="NetworkCredential"/>&gt;</c> delegate
-    /// that references the method used to find the credentials. The default value is
-    /// <see langword="null"/>.
+    ///   <para>
+    ///   A <c>Func&lt;<see cref="IIdentity"/>,
+    ///   <see cref="NetworkCredential"/>&gt;</c> delegate or
+    ///   <see langword="null"/> if not needed.
+    ///   </para>
+    ///   <para>
+    ///   It references the method used to find the credentials.
+    ///   </para>
+    ///   <para>
+    ///   The default value is <see langword="null"/>.
+    ///   </para>
     /// </value>
     /// <exception cref="ObjectDisposedException">
     /// This listener has been closed.