diff --git a/websocket-sharp/Net/Cookie.cs b/websocket-sharp/Net/Cookie.cs
index ab38cb46..aaaf9dc8 100644
--- a/websocket-sharp/Net/Cookie.cs
+++ b/websocket-sharp/Net/Cookie.cs
@@ -336,6 +336,10 @@ namespace WebSocketSharp.Net
                ? (int) span.TotalSeconds
                : 0;
       }
+
+      set {
+        _expires = DateTime.Now.AddSeconds ((double) value);
+      }
     }
 
     internal int[] Ports {
diff --git a/websocket-sharp/Net/CookieCollection.cs b/websocket-sharp/Net/CookieCollection.cs
index e36657ef..4c8c5480 100644
--- a/websocket-sharp/Net/CookieCollection.cs
+++ b/websocket-sharp/Net/CookieCollection.cs
@@ -451,10 +451,7 @@ namespace WebSocketSharp.Net
           if (val.Length == 0)
             continue;
 
-          var max = Int32.Parse (val.Unquote ());
-          var expires = DateTime.Now.AddSeconds ((double) max);
-          cookie.Expires = expires;
-
+          cookie.MaxAge = Int32.Parse (val.Unquote ());
           continue;
         }