diff --git a/src/ai/api/ai_error.hpp b/src/ai/api/ai_error.hpp
--- a/src/ai/api/ai_error.hpp
+++ b/src/ai/api/ai_error.hpp
@@ -61,6 +61,7 @@ public:
 		ERR_CAT_ROAD,     //!< Error messages related to building / maintaining roads.
 		ERR_CAT_ORDER,    //!< Error messages related to managing orders.
 		ERR_CAT_MARINE,   //!< Error messages related to building / removing ships, docks and channels.
+		ERR_CAT_WAYPOINT, //!< Error messages related to building / maintaining waypoints.
 
 		/**
 		 * DO NOT USE! The error bitsize determines how many errors can be stored in