diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 416316c..7a4b7eb 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -151,6 +151,8 @@
         self.assertRaises(TypeError, __import__, 1, 2, 3, 4)
         self.assertRaises(ValueError, __import__, '')
         self.assertRaises(TypeError, __import__, 'sys', name='sys')
+        # embedded null character
+        self.assertRaises(ModuleNotFoundError, __import__, 'string\x00')
 
     def test_abs(self):
         # int
@@ -1002,6 +1004,10 @@
             self.assertEqual(fp.read(300), 'XXX'*100)
             self.assertEqual(fp.read(1000), 'YYY'*100)
 
+        # embedded null bytes and characters
+        self.assertRaises(ValueError, open, 'a\x00b')
+        self.assertRaises(ValueError, open, b'a\x00b')
+
     def test_open_default_encoding(self):
         old_environ = dict(os.environ)
         try:
diff --git a/Lib/test/test_curses.py b/Lib/test/test_curses.py
index 3d8c50b..0d0b160 100644
--- a/Lib/test/test_curses.py
+++ b/Lib/test/test_curses.py
@@ -81,7 +81,7 @@
         win2 = curses.newwin(15,15, 5,5)
 
         for meth in [stdscr.addch, stdscr.addstr]:
-            for args in [('a'), ('a', curses.A_BOLD),
+            for args in [('a',), ('a', curses.A_BOLD),
                          (4,4, 'a'), (5,5, 'a', curses.A_BOLD)]:
                 with self.subTest(meth=meth.__qualname__, args=args):
                     meth(*args)
@@ -194,6 +194,15 @@
         self.assertRaises(ValueError, stdscr.instr, -2)
         self.assertRaises(ValueError, stdscr.instr, 2, 3, -2)
 
+    def test_embedded_null_chars(self):
+        # reject embedded null bytes and characters
+        stdscr = self.stdscr
+        for arg in ['a', b'a']:
+            with self.subTest(arg=arg):
+                self.assertRaises(ValueError, stdscr.addstr, 'a\0')
+                self.assertRaises(ValueError, stdscr.addnstr, 'a\0', 1)
+                self.assertRaises(ValueError, stdscr.insstr, 'a\0')
+                self.assertRaises(ValueError, stdscr.insnstr, 'a\0', 1)
 
     def test_module_funcs(self):
         "Test module-level functions"
diff --git a/Lib/test/test_grp.py b/Lib/test/test_grp.py
index 69095a3..e511947 100644
--- a/Lib/test/test_grp.py
+++ b/Lib/test/test_grp.py
@@ -50,6 +50,8 @@
         self.assertRaises(TypeError, grp.getgrgid)
         self.assertRaises(TypeError, grp.getgrnam)
         self.assertRaises(TypeError, grp.getgrall, 42)
+        # embedded null character
+        self.assertRaises(ValueError, grp.getgrnam, 'a\x00b')
 
         # try to get some errors
         bynames = {}
diff --git a/Lib/test/test_imp.py b/Lib/test/test_imp.py
index 4ece365..6f35f49 100644
--- a/Lib/test/test_imp.py
+++ b/Lib/test/test_imp.py
@@ -314,6 +314,10 @@
         loader.get_data(imp.__file__)  # File should be closed
         loader.get_data(imp.__file__)  # Will need to create a newly opened file
 
+    def test_load_source(self):
+        with self.assertRaisesRegex(ValueError, 'embedded null'):
+            imp.load_source(__name__, __file__ + "\0")
+
 
 class ReloadTests(unittest.TestCase):
 
diff --git a/Lib/test/test_locale.py b/Lib/test/test_locale.py
index 99fab58..650d737 100644
--- a/Lib/test/test_locale.py
+++ b/Lib/test/test_locale.py
@@ -339,9 +339,14 @@
         self.assertLess(locale.strcoll('a', 'b'), 0)
         self.assertEqual(locale.strcoll('a', 'a'), 0)
         self.assertGreater(locale.strcoll('b', 'a'), 0)
+        # embedded null character
+        self.assertRaises(ValueError, locale.strcoll, 'a\0', 'a')
+        self.assertRaises(ValueError, locale.strcoll, 'a', 'a\0')
 
     def test_strxfrm(self):
         self.assertLess(locale.strxfrm('a'), locale.strxfrm('b'))
+        # embedded null character
+        self.assertRaises(ValueError, locale.strxfrm, 'a\0')
 
 
 class TestEnUSCollation(BaseLocalizedTest, TestCollation):
diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
index f224212..810ec37 100644
--- a/Lib/test/test_time.py
+++ b/Lib/test/test_time.py
@@ -126,6 +126,10 @@
             except ValueError:
                 self.fail('conversion specifier: %r failed.' % format)
 
+        self.assertRaises(TypeError, time.strftime, b'%S', tt)
+        # embedded null character
+        self.assertRaises(ValueError, time.strftime, '%S\0', tt)
+
     def _bounds_checking(self, func):
         # Make sure that strftime() checks the bounds of the various parts
         # of the time tuple (0 is valid for *all* values).
diff --git a/Lib/test/test_winsound.py b/Lib/test/test_winsound.py
index 179e069..21437ef 100644
--- a/Lib/test/test_winsound.py
+++ b/Lib/test/test_winsound.py
@@ -98,6 +98,8 @@
         self.assertRaises(TypeError, winsound.PlaySound, "bad",
                           winsound.SND_MEMORY)
         self.assertRaises(TypeError, winsound.PlaySound, 1, 0)
+        # embedded null character
+        self.assertRaises(ValueError, winsound.PlaySound, 'bad\0', 0)
 
     def test_keyword_args(self):
         safe_PlaySound(flags=winsound.SND_ALIAS, sound="SystemExit")