--- a/src/ai/api/ai_error.hpp	Mon Apr 07 18:29:12 2008 +0000
+++ b/src/ai/api/ai_error.hpp	Mon Apr 07 18:32:42 2008 +0000
@@ -35,6 +35,7 @@
 		ERR_CAT_VEHICLE,  //!< Error messages related to building / maintaining vehicles.
 		ERR_CAT_STATION,  //!< Error messages related to building / maintaining stations.
 		ERR_CAT_BRIDGE,   //!< Error messages related to building / removing bridges.
+		ERR_CAT_TUNNEL,   //!< Error messages related to building / removing tunnels.
 
 		/**
 		 * DO NOT USE! The error bitsize determines how many errors can be stored in