--- a/src/ai/ai_threads.cpp	Mon Jun 16 00:07:49 2008 +0000
+++ b/src/ai/ai_threads.cpp	Mon Jun 16 14:43:19 2008 +0000
@@ -8,7 +8,6 @@
 #include "../debug.h"
 #include "../thread.h"
 #include "../fiber.hpp"
-#include "../vehicle_func.h"
 #include "../player_func.h"
 #include "ai.h"
 #include "ai_threads.h"
@@ -398,8 +397,6 @@
 	assert(thr != NULL);
 	/* Store if we were a success or not */
 	AIObject::SetLastCommandRes(success);
-	/* Store some values inside the AIObject static memory */
-	AIObject::SetNewVehicleID(_new_vehicle_id);
 
 	/* Resume the fiber now */
 	thr->Resume();

--- a/src/ai/api/ai_object.cpp	Mon Jun 16 00:07:49 2008 +0000
+++ b/src/ai/api/ai_object.cpp	Mon Jun 16 14:43:19 2008 +0000
@@ -97,6 +97,10 @@
 void AIObject::SetLastCommandRes(bool res)
 {
 	GetDoCommandStruct(_current_player)->last_command_res = res;
+	/* Also store the results of various global variables */
+	SetNewVehicleID(_new_vehicle_id);
+	SetNewSignID(_new_sign_id);
+	SetNewTunnelEndtile(_build_tunnel_endtile);
 }
 
 bool AIObject::GetLastCommandRes()
@@ -227,11 +231,8 @@
 	{
 #endif
 		/* For SinglePlayer we execute the command immediatly */
-		::DoCommandP(tile, p1, p2, NULL, procc);
-		/* Store some values inside the AIObject static memory */
-		SetNewVehicleID(_new_vehicle_id);
-		SetNewSignID(_new_sign_id);
-		SetNewTunnelEndtile(_build_tunnel_endtile);
+		if (!::DoCommandP(tile, p1, p2, NULL, procc)) res = CMD_ERROR;
+		SetLastCommandRes(!CmdFailed(res));
 
 		/* Suspend the AI player for 1 tick, so it simulates MultiPlayer */
 		::AI_SuspendPlayer(_current_player, GetDoCommandDelay());