diff --git a/.flake8 b/.flake8
index f97bdb63..8d4ecfb0 100644
--- a/.flake8
+++ b/.flake8
@@ -2,8 +2,6 @@
 exclude = .git,.tox,__pycache__,.eggs,build
 max-line-length = 100
 ignore =
-    # E231 missing whitespace after ','
-    E231,
     # E265 block comment should start with '# '
     E265,
     # E266 too many leading '#' for block comment
@@ -12,5 +10,3 @@ ignore =
     E402,
     # E722 do not use bare except
     E722,
-    # E741 ambiguous variable name 'l'
-    E741,
diff --git a/demos/benchmark/template_benchmark.py b/demos/benchmark/template_benchmark.py
index c0e67cec..03d94839 100755
--- a/demos/benchmark/template_benchmark.py
+++ b/demos/benchmark/template_benchmark.py
@@ -14,7 +14,8 @@ define('dump', default=False, help='print template generated code and exit')
 
 context = {
     'page_title': 'mitsuhiko\'s benchmark',
-    'table': [dict(a=1,b=2,c=3,d=4,e=5,f=6,g=7,h=8,i=9,j=10) for x in range(1000)]
+    'table': [dict(a=1, b=2, c=3, d=4, e=5,
+                   f=6, g=7, h=8, i=9, j=10) for x in range(1000)]
 }
 
 tmpl = Template("""\
diff --git a/maint/test/appengine/common/runtests.py b/maint/test/appengine/common/runtests.py
index ba89a7aa..ca7abe11 100644
--- a/maint/test/appengine/common/runtests.py
+++ b/maint/test/appengine/common/runtests.py
@@ -51,7 +51,7 @@ if __name__ == "__main__":
         for sig in [signal.SIGTERM, signal.SIGTERM, signal.SIGKILL]:
             os.kill(proc.pid, sig)
             res = os.waitpid(proc.pid, os.WNOHANG)
-            if res != (0,0):
+            if res != (0, 0):
                 break
             time.sleep(0.1)
         else:
diff --git a/tornado/test/gen_test.py b/tornado/test/gen_test.py
index d19d9930..eee8655b 100644
--- a/tornado/test/gen_test.py
+++ b/tornado/test/gen_test.py
@@ -1021,7 +1021,7 @@ class GenCoroutineTest(AsyncTestCase):
         self.finished = True
 
     @skipNotCPython
-    @unittest.skipIf((3,) < sys.version_info < (3,6),
+    @unittest.skipIf((3,) < sys.version_info < (3, 6),
                      "asyncio.Future has reference cycles")
     def test_coroutine_refcounting(self):
         # On CPython, tasks and their arguments should be released immediately
diff --git a/tornado/websocket.py b/tornado/websocket.py
index 4b1b220e..32012780 100644
--- a/tornado/websocket.py
+++ b/tornado/websocket.py
@@ -757,17 +757,17 @@ class WebSocketProtocol13(WebSocketProtocol):
         else:
             finbit = 0
         frame = struct.pack("B", finbit | opcode | flags)
-        l = len(data)
+        data_len = len(data)
         if self.mask_outgoing:
             mask_bit = 0x80
         else:
             mask_bit = 0
-        if l < 126:
-            frame += struct.pack("B", l | mask_bit)
-        elif l <= 0xFFFF:
-            frame += struct.pack("!BH", 126 | mask_bit, l)
+        if data_len < 126:
+            frame += struct.pack("B", data_len | mask_bit)
+        elif data_len <= 0xFFFF:
+            frame += struct.pack("!BH", 126 | mask_bit, data_len)
         else:
-            frame += struct.pack("!BQ", 127 | mask_bit, l)
+            frame += struct.pack("!BQ", 127 | mask_bit, data_len)
         if self.mask_outgoing:
             mask = os.urandom(4)
             data = mask + _websocket_mask(mask, data)