diff --git a/dist/pythonlibs/testrunner/spawn.py b/dist/pythonlibs/testrunner/spawn.py
index 8b6c05144c..60d06187d7 100644
--- a/dist/pythonlibs/testrunner/spawn.py
+++ b/dist/pythonlibs/testrunner/spawn.py
@@ -56,8 +56,8 @@ def _reset_board(env):
         pass
 
 
-def list_until(l, cond):
-    return l[:([i for i, e in enumerate(l) if cond(e)][0])]
+def list_until(list_, cond):
+    return list_[:([i for i, e in enumerate(list_) if cond(e)][0])]
 
 
 def find_exc_origin(exc_info):
diff --git a/dist/tools/bmp/bmp.py b/dist/tools/bmp/bmp.py
index 0a97b86711..83eac8acf3 100755
--- a/dist/tools/bmp/bmp.py
+++ b/dist/tools/bmp/bmp.py
@@ -72,11 +72,11 @@ def detect_probes():
     return gdb_ports, uart_ports
 
 
-# search device with specific serial number <snr> in list <l>
-def search_serial(snr, l):
-    for p in l:
-        if snr in p.serial_number:
-            return p.device
+# search device with specific serial number <snr> in a list of ports <ports>
+def search_serial(snr, ports):
+    for port in ports:
+        if snr in port.serial_number:
+            return port.device
 
 
 # parse GDB output for targets
diff --git a/tests/pbkdf2/tests/test_base.py b/tests/pbkdf2/tests/test_base.py
index c6a639929e..b7ceced0f4 100644
--- a/tests/pbkdf2/tests/test_base.py
+++ b/tests/pbkdf2/tests/test_base.py
@@ -25,10 +25,10 @@ def test(vectors, child):
         assert idx == 0
         return idx
 
-    def _safe_sendline(l):
-        assert len(l) < MAX_LINE
+    def _safe_sendline(line):
+        assert len(line) < MAX_LINE
         _safe_expect_exact('{ready}')
-        child.sendline(l)
+        child.sendline(line)
 
     for passwd, salt, iters, key in vectors:
         _safe_sendline(passwd)