diff --git a/libraries/AP_ExternalControl/AP_ExternalControl.h b/libraries/AP_ExternalControl/AP_ExternalControl.h
index 34228e2b7ab4ff..f1554a1a868f51 100644
--- a/libraries/AP_ExternalControl/AP_ExternalControl.h
+++ b/libraries/AP_ExternalControl/AP_ExternalControl.h
@@ -32,6 +32,15 @@ class AP_ExternalControl
         return false;
     }
 
+    /*
+        Set the target setpoint for path guidance: the closest position on the
+        path, the unit tangent to the path, and path curvature and direction.
+    */
+    virtual bool set_path_position_tangent_and_curvature(const Location &position_on_path,
+            Vector2f unit_path_tangent, const float path_curvature, const bool direction_is_ccw) WARN_IF_UNUSED {
+        return false;
+    }
+
     static AP_ExternalControl *get_singleton(void) WARN_IF_UNUSED {
         return singleton;
     }
@@ -42,7 +51,6 @@ class AP_ExternalControl
     static AP_ExternalControl *singleton;
 };
 
-
 namespace AP
 {
 AP_ExternalControl *externalcontrol();