diff --git a/libraries/AP_TECS/AP_TECS.h b/libraries/AP_TECS/AP_TECS.h
index e47122c9d0..6d6ed2c0bd 100644
--- a/libraries/AP_TECS/AP_TECS.h
+++ b/libraries/AP_TECS/AP_TECS.h
@@ -21,6 +21,7 @@
 #include <AP_AHRS/AP_AHRS.h>
 #include <AP_Param/AP_Param.h>
 #include <AP_Vehicle/AP_Vehicle.h>
+#include <Filter/AverageFilter.h>
 
 class AP_Landing;
 class AP_TECS {