diff --git a/pyperf/_formatter.py b/pyperf/_formatter.py
index 767faf2d..6c3a1eea 100644
--- a/pyperf/_formatter.py
+++ b/pyperf/_formatter.py
@@ -30,9 +30,9 @@ def format_filesize(size):
             return '%.0f byte' % size
 
     if size > 10 * 1024 * 1024:
-        return '%.1f MB' % (size / (1024.0 * 1024.0))
+        return '%.1f MiB' % (size / (1024.0 * 1024.0))
 
-    return '%.1f kB' % (size / 1024.0)
+    return '%.1f KiB' % (size / 1024.0)
 
 
 def format_filesizes(sizes):
diff --git a/pyperf/tests/test_metadata.py b/pyperf/tests/test_metadata.py
index 58a2481a..0e08304a 100644
--- a/pyperf/tests/test_metadata.py
+++ b/pyperf/tests/test_metadata.py
@@ -55,7 +55,7 @@ class CpuFunctionsTests(unittest.TestCase):
         stepping\t: 9
         microcode\t: 0x1c
         cpu MHz\t\t: 1287.554
-        cache size\t: 4096 KB
+        cache size\t: 4096 KiB
         physical id\t: 0
         siblings\t: 4
         core id\t\t: 0
@@ -82,7 +82,7 @@ class CpuFunctionsTests(unittest.TestCase):
         stepping\t: 9
         microcode\t: 0x1c
         cpu MHz\t\t: 1225.363
-        cache size\t: 4096 KB
+        cache size\t: 4096 KiB
         physical id\t: 0
         siblings\t: 4
         core id\t\t: 0
@@ -109,7 +109,7 @@ class CpuFunctionsTests(unittest.TestCase):
         stepping\t: 9
         microcode\t: 0x1c
         cpu MHz\t\t: 1200.101
-        cache size\t: 4096 KB
+        cache size\t: 4096 KiB
         physical id\t: 0
         siblings\t: 4
         core id\t\t: 1
diff --git a/pyperf/tests/test_perf_cli.py b/pyperf/tests/test_perf_cli.py
index 57f1dab1..6423c52b 100644
--- a/pyperf/tests/test_perf_cli.py
+++ b/pyperf/tests/test_perf_cli.py
@@ -556,13 +556,13 @@ def test_dump(self):
     def test_dump_track_memory(self):
         expected = """
             Run 1: calibrate the number of loops: 2^15
-            - calibrate 1: 7188.0 kB (loops: 2^15)
+            - calibrate 1: 7188.0 KiB (loops: 2^15)
             Run 2: 0 warmups, 1 value, 2^15 loops
-            - value 1: 7188.0 kB
+            - value 1: 7188.0 KiB
             Run 3: 0 warmups, 1 value, 2^15 loops
-            - value 1: 7192.0 kB
+            - value 1: 7192.0 KiB
             Run 4: 0 warmups, 1 value, 2^15 loops
-            - value 1: 7208.0 kB
+            - value 1: 7208.0 KiB
         """
         filename = os.path.join(TESTDIR, 'track_memory.json')
         stdout = self.run_command('dump', filename)
@@ -595,7 +595,7 @@ def test_dump_verbose(self):
               date: 2016-10-21 03:14:19.670631
               duration: 338 ms
               load_avg_1min: 0.29
-              mem_max_rss: 13.4 MB
+              mem_max_rss: 13.4 MiB
               runnable_threads: 1
               uptime: 2 day 2 hour 4 min
             Run 2: 1 warmup, 3 values, 8 loops
@@ -609,7 +609,7 @@ def test_dump_verbose(self):
               date: 2016-10-21 03:14:20.496710
               duration: 723 ms
               load_avg_1min: 0.29
-              mem_max_rss: 13.5 MB
+              mem_max_rss: 13.5 MiB
               runnable_threads: 1
               uptime: 2 day 2 hour 4 min
         """
@@ -689,7 +689,7 @@ def _check_track_memory(self, track_option):
                              '[1,2]*1000',
                              '-o', tmp_name)
             bench = pyperf.Benchmark.load(tmp_name)
-
+        
         self._check_track_memory_bench(bench, loops=5)
 
     def test_track_memory(self):
diff --git a/pyperf/tests/test_utils.py b/pyperf/tests/test_utils.py
index 85e3afba..edf8549c 100644
--- a/pyperf/tests/test_utils.py
+++ b/pyperf/tests/test_utils.py
@@ -146,9 +146,9 @@ def test_format_filesize(self):
         self.assertEqual(format_filesize(1),
                          '1 byte')
         self.assertEqual(format_filesize(10 * 1024),
-                         '10.0 kB')
+                         '10.0 KiB')
         self.assertEqual(format_filesize(12.4 * 1024 * 1024),
-                         '12.4 MB')
+                         '12.4 MiB')
 
     def test_get_python_names(self):
         self.assertEqual(utils.get_python_names('/usr/bin/python3.6',