diff --git a/websocket-sharp/Server/WebSocketServiceManager.cs b/websocket-sharp/Server/WebSocketServiceManager.cs
index bbe7fccf..1ed1e6fa 100644
--- a/websocket-sharp/Server/WebSocketServiceManager.cs
+++ b/websocket-sharp/Server/WebSocketServiceManager.cs
@@ -566,7 +566,7 @@ namespace WebSocketSharp.Server
       if (message == null || message.Length == 0)
         return Broadping ();
 
-      byte[] data;
+      byte[] data = null;
       var msg = _state.CheckIfStart () ?? WebSocket.CheckPingParameter (message, out data);
       if (msg != null) {
         _logger.Error (msg);
diff --git a/websocket-sharp/Server/WebSocketSessionManager.cs b/websocket-sharp/Server/WebSocketSessionManager.cs
index b745524c..051aa023 100644
--- a/websocket-sharp/Server/WebSocketSessionManager.cs
+++ b/websocket-sharp/Server/WebSocketSessionManager.cs
@@ -571,7 +571,7 @@ namespace WebSocketSharp.Server
       if (message == null || message.Length == 0)
         return Broadping ();
 
-      byte[] data;
+      byte[] data = null;
       var msg = _state.CheckIfStart () ?? WebSocket.CheckPingParameter (message, out data);
       if (msg != null) {
         _logger.Error (msg);