diff --git a/src/ai/api/ai_order.cpp b/src/ai/api/ai_order.cpp
index 3bde539be7..7522917516 100644
--- a/src/ai/api/ai_order.cpp
+++ b/src/ai/api/ai_order.cpp
@@ -509,6 +509,8 @@ static void _DoCommandReturnSetOrderFlags(class AIInstance *instance)
 
 	AIOrderFlags current = GetOrderFlags(vehicle_id, order_position);
 
+	EnforcePrecondition(false, (order_flags & AIOF_GOTO_NEAREST_DEPOT) == (current & AIOF_GOTO_NEAREST_DEPOT));
+
 	if ((current & AIOF_NON_STOP_FLAGS) != (order_flags & AIOF_NON_STOP_FLAGS)) {
 		return AIObject::DoCommand(0, vehicle_id | (order_position << 20), (order_flags & AIOF_NON_STOP_FLAGS) << 4 | MOF_NON_STOP, CMD_MODIFY_ORDER, NULL, &_DoCommandReturnSetOrderFlags);
 	}
diff --git a/src/ai/api/ai_order.hpp b/src/ai/api/ai_order.hpp
index bfd10a0a93..14f07e6de0 100644
--- a/src/ai/api/ai_order.hpp
+++ b/src/ai/api/ai_order.hpp
@@ -457,6 +457,7 @@ public:
 	 * @param order_flags The new flags given to the order.
 	 * @pre IsValidVehicleOrder(vehicle_id, order_position).
 	 * @pre AreOrderFlagsValid(GetOrderDestination(vehicle_id, order_position), order_flags).
+	 * @pre (order_flags & AIOF_GOTO_NEAREST_DEPOT) == (GetOrderFlags(vehicle_id, order_position) & AIOF_GOTO_NEAREST_DEPOT).
 	 * @exception AIError::ERR_OWNED_BY_ANOTHER_COMPANY
 	 * @return True if and only if the order was changed.
 	 */