diff --git a/tornado/locks.py b/tornado/locks.py
index 3b1c08da9..d05c921ff 100644
--- a/tornado/locks.py
+++ b/tornado/locks.py
@@ -122,7 +122,7 @@ def wait(
         """
         waiter: Future[bool] = Future()
         self._waiters.append(waiter)
-        if timeout:
+        if timeout is not None:
 
             def on_timeout() -> None:
                 if not waiter.done():
@@ -421,7 +421,7 @@ def acquire(
             waiter.set_result(_ReleasingContextManager(self))
         else:
             self._waiters.append(waiter)
-            if timeout:
+            if timeout is not None:
 
                 def on_timeout() -> None:
                     if not waiter.done():
diff --git a/tornado/queues.py b/tornado/queues.py
index 41766eef7..89403d7a3 100644
--- a/tornado/queues.py
+++ b/tornado/queues.py
@@ -55,7 +55,7 @@ class QueueFull(Exception):
 
 
 def _set_timeout(future: Future, timeout: None | float | datetime.timedelta) -> None:
-    if timeout:
+    if timeout is not None:
 
         def on_timeout() -> None:
             if not future.done():
diff --git a/tornado/test/queues_test.py b/tornado/test/queues_test.py
index efbb1c319..c29eea9c0 100644
--- a/tornado/test/queues_test.py
+++ b/tornado/test/queues_test.py
@@ -117,6 +117,14 @@ def test_get_timeout(self):
         q.put_nowait(0)
         self.assertEqual(0, (yield get))
 
+    @gen_test
+    def test_get_zero_timeout(self):
+        q: queues.Queue[int] = queues.Queue()
+        with self.assertRaises(TimeoutError):
+            yield q.get(timeout=timedelta(seconds=0))
+        with self.assertRaises(TimeoutError):
+            yield q.get(timeout=0)
+
     @gen_test
     def test_get_timeout_preempted(self):
         q: queues.Queue[int] = queues.Queue()