diff --git a/contrib/python3-whitelist b/contrib/python3-whitelist
--- a/contrib/python3-whitelist
+++ b/contrib/python3-whitelist
@@ -362,6 +362,7 @@
 test-linelog.py
 test-linerange.py
 test-locate.t
+test-lock.py
 test-lock-badness.t
 test-log-exthook.t
 test-log-linerange.t
diff --git a/tests/test-lock.py b/tests/test-lock.py
--- a/tests/test-lock.py
+++ b/tests/test-lock.py
@@ -290,7 +290,7 @@
             self.fail("unexpected lock acquisition")
         except error.LockHeld as why:
             self.assertTrue(why.errno == errno.ETIMEDOUT)
-            self.assertTrue(why.locker == "")
+            self.assertTrue(why.locker == b"")
             state.assertlockexists(False)
 
 if __name__ == '__main__':