diff --git a/django/utils/archive.py b/django/utils/archive.py
index ea948fe44f..9c2d4ac01b 100644
--- a/django/utils/archive.py
+++ b/django/utils/archive.py
@@ -141,7 +141,7 @@ class TarArchive(BaseArchive):
                 name = self.split_leading_dir(name)[1]
             filename = os.path.join(to_path, name)
             if member.isdir():
-                if not os.path.exists(filename):
+                if filename and not os.path.exists(filename):
                     os.makedirs(filename)
             else:
                 try:
@@ -153,7 +153,7 @@ class TarArchive(BaseArchive):
                            (name, member.name, sys.exc_info()[1]))
                 else:
                     dirname = os.path.dirname(filename)
-                    if not os.path.exists(dirname):
+                    if dirname and not os.path.exists(dirname):
                         os.makedirs(dirname)
                     with open(filename, 'wb') as outfile:
                         shutil.copyfileobj(extracted, outfile)
diff --git a/tests/regressiontests/utils/crypto.py b/tests/regressiontests/utils/crypto.py
index f025ffa790..5c861c6357 100644
--- a/tests/regressiontests/utils/crypto.py
+++ b/tests/regressiontests/utils/crypto.py
@@ -126,8 +126,8 @@ class TestUtilsCryptoPBKDF2(unittest.TestCase):
         times as long as running with 1 iteration.
         """
         n1, n2 = 100, 10000
-        elapsed = lambda f: timeit.timeit(f, number=1)
-        t1 = elapsed(lambda: pbkdf2("password", "salt", iterations=n1))
-        t2 = elapsed(lambda: pbkdf2("password", "salt", iterations=n2))
+        elapsed = lambda f: timeit.Timer(f, 'from django.utils.crypto import pbkdf2').timeit(number=1)
+        t1 = elapsed('pbkdf2("password", "salt", iterations=%d)' % n1)
+        t2 = elapsed('pbkdf2("password", "salt", iterations=%d)' % n2)
         measured_scale_exponent = math.log(t2 / t1, n2 / n1)
         self.assertLess(measured_scale_exponent, 1.1)