diff --git a/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp b/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
index 50bc349744..8cfeadeea6 100644
--- a/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
+++ b/libraries/AP_NavEKF3/AP_NavEKF3_Measurements.cpp
@@ -4,6 +4,7 @@
 #include <GCS_MAVLink/GCS.h>
 #include <AP_Logger/AP_Logger.h>
 #include <AP_DAL/AP_DAL.h>
+#include <AP_InternalError/AP_InternalError.h>
 
 /********************************************************
 *              OPT FLOW AND RANGE FINDER                *