diff --git a/window.c b/window.c
index c5bc834bab..1b4b3773c2 100644
--- a/window.c
+++ b/window.c
@@ -716,6 +716,7 @@ void ResetWindowSystem(void)
 {
 	UnInitWindowSystem();
 	InitWindowSystem();
+	memset(&_thd, 0, sizeof(TileHighlightData));
 }
 
 static void DecreaseWindowCounters(void)