diff --git a/libraries/SITL/SIM_AirSim.cpp b/libraries/SITL/SIM_AirSim.cpp
index 37a96d6c7f..0a3d0d8c0f 100644
--- a/libraries/SITL/SIM_AirSim.cpp
+++ b/libraries/SITL/SIM_AirSim.cpp
@@ -10,6 +10,7 @@
 
 #include <AP_HAL/AP_HAL.h>
 #include <AP_Logger/AP_Logger.h>
+#include <AP_HAL/utility/replace.h>
 
 extern const AP_HAL::HAL& hal;