diff --git a/iot/include/alibabacloud/iot/model/RRpcResult.h b/iot/include/alibabacloud/iot/model/RRpcResult.h
index 5775b10d8..5874a5104 100644
--- a/iot/include/alibabacloud/iot/model/RRpcResult.h
+++ b/iot/include/alibabacloud/iot/model/RRpcResult.h
@@ -52,7 +52,7 @@ namespace AlibabaCloud
 				std::string errorMessage_;
 				std::string code_;
 				bool success_;
-				long messageId_;
+				unsigned long long messageId_;
 
 			};
 		}
diff --git a/iot/src/model/RRpcResult.cc b/iot/src/model/RRpcResult.cc
index 51723eceb..712c7b9fc 100644
--- a/iot/src/model/RRpcResult.cc
+++ b/iot/src/model/RRpcResult.cc
@@ -50,7 +50,7 @@ void RRpcResult::parse(const std::string &payload)
 	if(!value["PayloadBase64Byte"].isNull())
 		payloadBase64Byte_ = value["PayloadBase64Byte"].asString();
 	if(!value["MessageId"].isNull())
-		messageId_ = std::stol(value["MessageId"].asString());
+		messageId_ = std::stoull(value["MessageId"].asString());
 
 }