diff --git a/libraries/AC_WPNav/AC_WPNav_OA.cpp b/libraries/AC_WPNav/AC_WPNav_OA.cpp
index 373161b704..97c65eb5f2 100644
--- a/libraries/AC_WPNav/AC_WPNav_OA.cpp
+++ b/libraries/AC_WPNav/AC_WPNav_OA.cpp
@@ -80,8 +80,8 @@ bool AC_WPNav_OA::update_wpnav()
         }
 
         // convert origin and destination to Locations and pass into oa
-        const Location origin_loc(_origin_oabak, _terrain_alt ? Location::AltFrame::ABOVE_TERRAIN : Location::AltFrame::ABOVE_ORIGIN);
-        const Location destination_loc(_destination_oabak, _terrain_alt ? Location::AltFrame::ABOVE_TERRAIN : Location::AltFrame::ABOVE_ORIGIN);
+        const Location origin_loc(_origin_oabak, _terrain_alt_oabak ? Location::AltFrame::ABOVE_TERRAIN : Location::AltFrame::ABOVE_ORIGIN);
+        const Location destination_loc(_destination_oabak, _terrain_alt_oabak ? Location::AltFrame::ABOVE_TERRAIN : Location::AltFrame::ABOVE_ORIGIN);
         Location oa_origin_new, oa_destination_new;
         const AP_OAPathPlanner::OA_RetState oa_retstate = oa_ptr->mission_avoidance(current_loc, origin_loc, destination_loc, oa_origin_new, oa_destination_new);
         switch (oa_retstate) {