diff --git a/psutil/tests/test_linux.py b/psutil/tests/test_linux.py
index 77958ada8..09fed4e46 100755
--- a/psutil/tests/test_linux.py
+++ b/psutil/tests/test_linux.py
@@ -842,25 +842,6 @@ def open_mock(name, *args, **kwargs):
                     freq = psutil.cpu_freq()
                     self.assertEqual(freq.current, 200)
 
-        # Also test that NotImplementedError is raised in case no
-        # current freq file is present.
-
-        def open_mock(name, *args, **kwargs):
-            if name.endswith('/scaling_cur_freq'):
-                raise IOError(errno.ENOENT, "")
-            elif name.endswith('/cpuinfo_cur_freq'):
-                raise IOError(errno.ENOENT, "")
-            elif name == '/proc/cpuinfo':
-                raise IOError(errno.ENOENT, "")
-            else:
-                return orig_open(name, *args, **kwargs)
-
-        orig_open = open
-        patch_point = 'builtins.open' if PY3 else '__builtin__.open'
-        with mock.patch(patch_point, side_effect=open_mock):
-            with mock.patch('os.path.exists', return_value=True):
-                self.assertRaises(NotImplementedError, psutil.cpu_freq)
-
 
 @unittest.skipIf(not LINUX, "LINUX only")
 class TestSystemCPUStats(unittest.TestCase):
diff --git a/psutil/tests/test_system.py b/psutil/tests/test_system.py
index 83d7ef304..e04e120b3 100755
--- a/psutil/tests/test_system.py
+++ b/psutil/tests/test_system.py
@@ -364,17 +364,16 @@ def test_per_cpu_times_2(self):
         # Simulate some work load then make sure time have increased
         # between calls.
         tot1 = psutil.cpu_times(percpu=True)
-        stop_at = time.time() + 0.1
+        giveup_at = time.time() + 1
         while True:
-            if time.time() >= stop_at:
-                break
-        tot2 = psutil.cpu_times(percpu=True)
-        for t1, t2 in zip(tot1, tot2):
-            t1, t2 = sum(t1), sum(t2)
-            difference = t2 - t1
-            if difference >= 0.05:
-                return
-        self.fail()
+            if time.time() >= giveup_at:
+                return self.fail("timeout")
+            tot2 = psutil.cpu_times(percpu=True)
+            for t1, t2 in zip(tot1, tot2):
+                t1, t2 = psutil._cpu_busy_time(t1), psutil._cpu_busy_time(t2)
+                difference = t2 - t1
+                if difference >= 0.05:
+                    return
 
     def test_cpu_times_comparison(self):
         # Make sure the sum of all per cpu times is almost equal to