diff --git a/libraries/AP_RPM/RPM_SITL.cpp b/libraries/AP_RPM/RPM_SITL.cpp
index ff5525b36d..e002cdce01 100644
--- a/libraries/AP_RPM/RPM_SITL.cpp
+++ b/libraries/AP_RPM/RPM_SITL.cpp
@@ -25,7 +25,7 @@ extern const AP_HAL::HAL& hal;
    open the sensor in constructor
 */
 AP_RPM_SITL::AP_RPM_SITL(AP_RPM &_ap_rpm, uint8_t _instance, AP_RPM::RPM_State &_state) :
-	AP_RPM_Backend(_ap_rpm, instance, _state)
+	AP_RPM_Backend(_ap_rpm, _instance, _state)
 {
     sitl = (SITL::SITL *)AP_Param::find_object("SIM_");
     instance = _instance;