diff --git a/src/modbusException.cpp b/src/modbusException.cpp
index a9cee53..ec29b0d 100644
--- a/src/modbusException.cpp
+++ b/src/modbusException.cpp
@@ -54,8 +54,8 @@ std::vector<uint8_t> ModbusException::toRaw() const noexcept {
   std::vector<uint8_t> result(3);
 
   result[0] = _slaveId;
-  result[1] = static_cast<uint8_t>(_errorCode | 0b10000000);
-  result[2] = static_cast<uint8_t>(_functionCode);
+  result[1] = static_cast<uint8_t>(_functionCode | 0b10000000);
+  result[2] = static_cast<uint8_t>(_errorCode);
 
   return result;
 }