diff --git a/websocket-sharp/Net/HttpListener.cs b/websocket-sharp/Net/HttpListener.cs
index 96b42e05..feba1a10 100644
--- a/websocket-sharp/Net/HttpListener.cs
+++ b/websocket-sharp/Net/HttpListener.cs
@@ -765,11 +765,18 @@ namespace WebSocketSharp.Net
     public HttpListenerContext GetContext ()
     {
       CheckDisposed ();
-      if (_prefixes.Count == 0)
-        throw new InvalidOperationException ("The listener has no URI prefix on which listens.");
 
-      if (!_listening)
-        throw new InvalidOperationException ("The listener hasn't been started.");
+      if (_prefixes.Count == 0) {
+        var msg = "The listener has no URI prefix on which listens.";
+
+        throw new InvalidOperationException (msg);
+      }
+
+      if (!_listening) {
+        var msg = "The listener has not been started.";
+
+        throw new InvalidOperationException (msg);
+      }
 
       var ares = BeginGetContext (new HttpListenerAsyncResult (null, null));
       ares.InGet = true;