diff --git a/requirements-tests.txt b/requirements-tests.txt
index d7f65a9..b7edffd 100644
--- a/requirements-tests.txt
+++ b/requirements-tests.txt
@@ -3,5 +3,5 @@ attrs==19.3.0
 pytest==5.4.2
 pytest-cov==2.8.1
 mock==2.0.0
-flake8==3.6.0
+flake8==3.8.1
 pyflakes==2.2.0
diff --git a/sshuttle/ssnet.py b/sshuttle/ssnet.py
index 5f30c42..f6044aa 100644
--- a/sshuttle/ssnet.py
+++ b/sshuttle/ssnet.py
@@ -61,14 +61,14 @@ NET_ERRS = [errno.ECONNREFUSED, errno.ETIMEDOUT,
             errno.ECONNRESET]
 
 
-def _add(l, elem):
-    if elem not in l:
-        l.append(elem)
+def _add(socks, elem):
+    if elem not in socks:
+        socks.append(elem)
 
 
-def _fds(l):
+def _fds(socks):
     out = []
-    for i in l:
+    for i in socks:
         try:
             out.append(i.fileno())
         except AttributeError: