--- a/src/command.cpp	Wed Jan 16 00:33:28 2008 +0000
+++ b/src/command.cpp	Wed Jan 16 01:18:15 2008 +0000
@@ -20,6 +20,7 @@
 #include "debug.h"
 #include "player_func.h"
 #include "player_base.h"
+#include "signal_func.h"
 
 #include "table/strings.h"
 
@@ -642,6 +643,9 @@
 
 	SubtractMoneyFromPlayer(res2);
 
+	/* update signals if needed */
+	UpdateSignalsInBuffer();
+
 	if (IsLocalPlayer() && _game_mode != GM_EDITOR) {
 		if (res2.GetCost() != 0 && tile != 0) ShowCostOrIncomeAnimation(x, y, GetSlopeZ(x, y), res2.GetCost());
 		if (_additional_cash_required != 0) {