diff --git a/.arclint b/.arclint
--- a/.arclint
+++ b/.arclint
@@ -26,7 +26,7 @@
             "include": "(\\.py$)",
             "flags": [
                 "--select=E,W,F401,F402,F403,F404,F405,F406,F407,F601,F602,F621,F622,F631,F701,F702,F703,F704,F705,F706,F707,F811,F812,F821,F822,F823,F831,F841",
-                "--ignore=E501,E704,E722,E731,W503,W504"
+                "--ignore=E501,E704,E722,W503,W504"
             ]
         },
         "lint-format-strings": {
diff --git a/test/functional/wallet_multiwallet.py b/test/functional/wallet_multiwallet.py
--- a/test/functional/wallet_multiwallet.py
+++ b/test/functional/wallet_multiwallet.py
@@ -26,8 +26,9 @@
     def run_test(self):
         node = self.nodes[0]
 
-        data_dir = lambda *p: os.path.join(node.datadir, 'regtest', *p)
-        wallet_dir = lambda *p: data_dir('wallets', *p)
+        def data_dir(*p): return os.path.join(node.datadir, 'regtest', *p)
+
+        def wallet_dir(*p): return data_dir('wallets', *p)
 
         def wallet(name): return node.get_wallet_rpc(name)