diff --git a/IPython/core/magics/execution.py b/IPython/core/magics/execution.py
index 961dc5c7af..a860318b71 100644
--- a/IPython/core/magics/execution.py
+++ b/IPython/core/magics/execution.py
@@ -1598,11 +1598,11 @@ def _format_time(timespan, precision=3):
     # See bug: https://bugs.launchpad.net/ipython/+bug/348466
     # Try to prevent crashes by being more secure than it needs to
     # E.g. eclipse is able to print a µ, but has no sys.stdout.encoding set.
-    units = [u"s", u"ms",u'us',"ns"] # the safe value
-    if hasattr(sys.stdout, 'encoding') and sys.stdout.encoding:
+    units = ["s", "ms", "us", "ns"]  # the safe value
+    if hasattr(sys.stdout, "encoding") and sys.stdout.encoding:
         try:
-            u'\u03bc'.encode(sys.stdout.encoding)
-            units = [u"s", u"ms",u'\u03bcs',"ns"]
+            "\u03bc".encode(sys.stdout.encoding)
+            units = ["s", "ms", "\u03bcs", "ns"]
         except:
             pass
     scaling = [1, 1e3, 1e6, 1e9]
diff --git a/IPython/core/tests/test_magic.py b/IPython/core/tests/test_magic.py
index c2cad41542..c757b9cf62 100644
--- a/IPython/core/tests/test_magic.py
+++ b/IPython/core/tests/test_magic.py
@@ -529,12 +529,14 @@ def test_time_local_ns():
     assert ip.user_ns["myvar"] == 1
     del ip.user_ns["myvar"]
 
+
 def test_time_microseconds_display():
     """Ensure ASCII is used when necessary"""
-    with mock.patch('sys.stdout', io.TextIOWrapper(StringIO(), encoding='utf-8')):
-        assert execution._format_time(0.000001) == '1 \u03bcs'
-    with mock.patch('sys.stdout', io.TextIOWrapper(StringIO(), encoding='ascii')):
-        assert execution._format_time(0.000001) == '1 us'
+    with mock.patch("sys.stdout", io.TextIOWrapper(StringIO(), encoding="utf-8")):
+        assert execution._format_time(0.000001) == "1 \u03bcs"
+    with mock.patch("sys.stdout", io.TextIOWrapper(StringIO(), encoding="ascii")):
+        assert execution._format_time(0.000001) == "1 us"
+
 
 # Test %%capture magic. Added to test issue #13926
 def test_capture():