--- a/src/ai/api/ai_sign.cpp	Thu Jun 12 21:54:34 2008 +0000
+++ b/src/ai/api/ai_sign.cpp	Fri Jun 13 13:07:31 2008 +0000
@@ -11,6 +11,7 @@
 #include "../../string_func.h"
 #include "../../strings_func.h"
 #include "../../tile_map.h"
+#include "../../player_func.h"
 
 /* static */ SignID AISign::GetMaxSignID()
 {
@@ -19,12 +20,13 @@
 
 /* static */ bool AISign::IsValidSign(SignID sign_id)
 {
-	return ::IsValidSignID(sign_id);
+	return ::IsValidSignID(sign_id) && ::GetSign(sign_id)->owner == _current_player;
 }
 
 /* static */ char *AISign::GetText(SignID sign_id)
 {
 	if (!IsValidSign(sign_id)) return NULL;
+
 	static const int len = 64;
 	char *sign_name = MallocT<char>(len);
 
@@ -37,17 +39,11 @@
 /* static */ TileIndex AISign::GetLocation(SignID sign_id)
 {
 	if (!IsValidSign(sign_id)) return INVALID_TILE;
+
 	const Sign *sign = ::GetSign(sign_id);
 	return ::TileVirtXY(sign->x, sign->y);
 }
 
-/* static */ AICompany::CompanyID AISign::GetOwner(SignID sign_id)
-{
-	if (!IsValidSign(sign_id)) return AICompany::INVALID_COMPANY;
-	const Sign *sign = ::GetSign(sign_id);
-	return (AICompany::CompanyID)(byte)sign->owner;
-}
-
 /* static */ bool AISign::RemoveSign(SignID sign_id)
 {
 	EnforcePrecondition(false, IsValidSign(sign_id));