diff --git a/libraries/AP_HAL_AVR_SITL/SITL_State.cpp b/libraries/AP_HAL_AVR_SITL/SITL_State.cpp
index c067789e5a..094fec63eb 100644
--- a/libraries/AP_HAL_AVR_SITL/SITL_State.cpp
+++ b/libraries/AP_HAL_AVR_SITL/SITL_State.cpp
@@ -495,6 +495,9 @@ void SITL_State::_simulator_output(void)
 	// setup wind control
     float wind_speed = _sitl->wind_speed * 100;
     float altitude = _barometer?_barometer->get_altitude():0;
+    if (altitude < 0) {
+        altitude = 0;
+    }
     if (altitude < 60) {
         wind_speed *= altitude / 60.0f;
     }