diff --git a/libraries/AP_AHRS/AP_AHRS.cpp b/libraries/AP_AHRS/AP_AHRS.cpp
index 4780b75043a730..b4e08ea955fce6 100644
--- a/libraries/AP_AHRS/AP_AHRS.cpp
+++ b/libraries/AP_AHRS/AP_AHRS.cpp
@@ -3170,7 +3170,7 @@ uint8_t AP_AHRS::get_active_airspeed_index() const
 #if HAL_NAVEKF3_AVAILABLE
     if (active_EKF_type() == EKFType::THREE) {
         uint8_t ret = EKF3.getActiveAirspeed();
-        if (ret != 255 && airspeed->healthy(ret) && airspeed->use(ret)) {
+        if (ret != UINT8_MAX && airspeed->healthy(ret) && airspeed->use(ret)) {
             return ret;
         }
     }
diff --git a/libraries/AP_NavEKF3/AP_NavEKF3.cpp b/libraries/AP_NavEKF3/AP_NavEKF3.cpp
index 26bbeffc23d5e8..fef08de424c792 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3.cpp
@@ -1331,7 +1331,7 @@ uint8_t NavEKF3::getActiveAirspeed() const
     if (core) {
         return core[primary].getActiveAirspeed();
     } else {
-        return 255;
+        return UINT8_MAX;
     }
 }