diff --git a/websocket-sharp/Net/HttpListenerResponse.cs b/websocket-sharp/Net/HttpListenerResponse.cs
index b088c94a..0c8b7392 100644
--- a/websocket-sharp/Net/HttpListenerResponse.cs
+++ b/websocket-sharp/Net/HttpListenerResponse.cs
@@ -935,12 +935,29 @@ namespace WebSocketSharp.Net
     /// append.
     /// </param>
     /// <exception cref="ArgumentNullException">
-    /// <paramref name="name"/> is <see langword="null"/> or empty.
+    /// <paramref name="name"/> is <see langword="null"/>.
     /// </exception>
     /// <exception cref="ArgumentException">
     ///   <para>
-    ///   <paramref name="name"/> or <paramref name="value"/> contains
-    ///   an invalid character.
+    ///   <paramref name="name"/> is an empty string.
+    ///   </para>
+    ///   <para>
+    ///   -or-
+    ///   </para>
+    ///   <para>
+    ///   <paramref name="name"/> is a string of spaces.
+    ///   </para>
+    ///   <para>
+    ///   -or-
+    ///   </para>
+    ///   <para>
+    ///   <paramref name="name"/> contains an invalid character.
+    ///   </para>
+    ///   <para>
+    ///   -or-
+    ///   </para>
+    ///   <para>
+    ///   <paramref name="value"/> contains an invalid character.
     ///   </para>
     ///   <para>
     ///   -or-