do not allow reading negative values with getstr()
diff --git a/Lib/test/test_curses.py b/Lib/test/test_curses.py
index e08fe12..ce5f2a5 100644
--- a/Lib/test/test_curses.py
+++ b/Lib/test/test_curses.py
@@ -185,6 +185,9 @@
         if hasattr(curses, 'enclose'):
             stdscr.enclose()
 
+        self.assertRaises(ValueError, stdscr.getstr, -400)
+        self.assertRaises(ValueError, stdscr.getstr, 2, 3, -400)
+
 
     def test_module_funcs(self):
         "Test module-level functions"