diff --git a/lcl/include/screen.inc b/lcl/include/screen.inc
index 034d2b5798..3c7bb4c751 100644
--- a/lcl/include/screen.inc
+++ b/lcl/include/screen.inc
@@ -704,6 +704,8 @@ end;
 
 function TScreen.GetMonitor(Index: Integer): TMonitor;
 begin
+  if FMonitors.Count = 0 then
+    UpdateMonitors;
   Result := FMonitors[Index];
 end;