--- a/order_cmd.c	Mon Apr 11 20:19:41 2005 +0000
+++ b/order_cmd.c	Mon Apr 11 20:54:25 2005 +0000
@@ -7,7 +7,6 @@
 #include "player.h"
 #include "news.h"
 #include "saveload.h"
-#include "debug.h"
 
 enum {
 	/* Max orders: 64000 (64 * 1000) */
@@ -362,13 +361,8 @@
 			if (v->type == VEH_Train)
 				v->u.rail.days_since_order_progr = 0;
 
-			if (v->type == VEH_Road && v->u.road.slot != NULL) {
-				//Clear the slot ClearSlot() of roadveh_cmd.c
-				DEBUG(ms, 3) ("Multistop: Clearing slot %d at 0x%x", v->u.road.slotindex, v->dest_tile);
-				v->u.road.slot = NULL;
-				v->u.road.slot_age = 0;
-				v->u.road.slot->slot[v->u.road.slotindex] = INVALID_SLOT;
-			}
+			if (v->type == VEH_Road)
+				ClearSlot(v, v->u.road.slot);
 		}
 
 		/* NON-stop flag is misused to see if a train is in a station that is

--- a/roadveh_cmd.c	Mon Apr 11 20:19:41 2005 +0000
+++ b/roadveh_cmd.c	Mon Apr 11 20:54:25 2005 +0000
@@ -229,13 +229,16 @@
 	return 0;
 }
 
-static inline void ClearSlot(Vehicle *v, RoadStop *rs)
+void ClearSlot(Vehicle *v, RoadStop *rs)
 {
 	DEBUG(ms, 3) ("Multistop: Clearing slot %d at 0x%x", v->u.road.slotindex, rs->xy);
 	v->u.road.slot = NULL;
 	v->u.road.slot_age = 0;
-	if (rs != NULL)
+	if (rs != NULL) {
+		// check that the slot is indeed assigned to the same vehicle
+		assert(rs->slot[v->u.road.slotindex] == v->index);
 		rs->slot[v->u.road.slotindex] = INVALID_SLOT;
+ }
 }
 
 //  p1 = vehicle index in GetVehicle()

--- a/station.h	Mon Apr 11 20:19:41 2005 +0000
+++ b/station.h	Mon Apr 11 20:54:25 2005 +0000
@@ -270,6 +270,7 @@
 uint GetNumRoadStops(const Station *st, RoadStopType type);
 RoadStop * GetPrimaryRoadStop(const Station *st, RoadStopType type);
 RoadStop * AllocateRoadStop( void );
+void ClearSlot(Vehicle *v, RoadStop *rs);
 
 static inline bool IsTrainStationTile(uint tile) {
 	return IsTileType(tile, MP_STATION) && IS_BYTE_INSIDE(_map5[tile], 0, 8);