diff --git a/src/wallet/wallet_rpc_server.cpp b/src/wallet/wallet_rpc_server.cpp
index 228e43678..403e2bb86 100644
--- a/src/wallet/wallet_rpc_server.cpp
+++ b/src/wallet/wallet_rpc_server.cpp
@@ -88,7 +88,7 @@ namespace tools
   }
 
   //------------------------------------------------------------------------------------------------------------------------------
-  bool wallet_rpc_server::validate_transfer(const std::list<wallet_rpc::transfer_destination> destinations, const std::string payment_id, std::vector<cryptonote::tx_destination_entry>& dsts, std::vector<uint8_t> extra, epee::json_rpc::error& er)
+  bool wallet_rpc_server::validate_transfer(const std::list<wallet_rpc::transfer_destination> destinations, const std::string payment_id, std::vector<cryptonote::tx_destination_entry>& dsts, std::vector<uint8_t>& extra, epee::json_rpc::error& er)
   {
     for (auto it = destinations.begin(); it != destinations.end(); it++)
     {
diff --git a/src/wallet/wallet_rpc_server.h b/src/wallet/wallet_rpc_server.h
index 170f215f7..1164883e2 100644
--- a/src/wallet/wallet_rpc_server.h
+++ b/src/wallet/wallet_rpc_server.h
@@ -49,7 +49,7 @@ namespace tools
       //json_rpc
       bool on_getbalance(const wallet_rpc::COMMAND_RPC_GET_BALANCE::request& req, wallet_rpc::COMMAND_RPC_GET_BALANCE::response& res, epee::json_rpc::error& er, connection_context& cntx);
       bool on_getaddress(const wallet_rpc::COMMAND_RPC_GET_ADDRESS::request& req, wallet_rpc::COMMAND_RPC_GET_ADDRESS::response& res, epee::json_rpc::error& er, connection_context& cntx);
-      bool validate_transfer(const std::list<wallet_rpc::transfer_destination> destinations, const std::string payment_id, std::vector<cryptonote::tx_destination_entry>& dsts, std::vector<uint8_t> extra, epee::json_rpc::error& er);
+      bool validate_transfer(const std::list<wallet_rpc::transfer_destination> destinations, const std::string payment_id, std::vector<cryptonote::tx_destination_entry>& dsts, std::vector<uint8_t>& extra, epee::json_rpc::error& er);
       bool on_transfer(const wallet_rpc::COMMAND_RPC_TRANSFER::request& req, wallet_rpc::COMMAND_RPC_TRANSFER::response& res, epee::json_rpc::error& er, connection_context& cntx);
       bool on_transfer_split(const wallet_rpc::COMMAND_RPC_TRANSFER_SPLIT::request& req, wallet_rpc::COMMAND_RPC_TRANSFER_SPLIT::response& res, epee::json_rpc::error& er, connection_context& cntx);
       bool on_store(const wallet_rpc::COMMAND_RPC_STORE::request& req, wallet_rpc::COMMAND_RPC_STORE::response& res, epee::json_rpc::error& er, connection_context& cntx);