diff --git a/tests/test_prarallel_limiter.py b/tests/test_prarallel_limiter.py
index 05133cd1..84b93e04 100644
--- a/tests/test_prarallel_limiter.py
+++ b/tests/test_prarallel_limiter.py
@@ -1,3 +1,8 @@
+import threading
+import time
+from typing import Optional
+
+import werkzeug.exceptions
 from flask_login import login_user
 
 from app.parallel_limiter import _InnerLock
@@ -11,3 +16,27 @@ def test_parallel_limiter(flask_app):
         pl = _InnerLock("test", max_wait_secs=1)
         for loop_id in range(10):
             assert pl(lambda x: x)(loop_id) == loop_id
+
+
+def sleep_thread(pl: _InnerLock, sem: Optional[threading.Semaphore] = None):
+    if sem is not None:
+        sem.release()
+    pl(time.sleep)(1)
+
+
+def test_too_many_requests(flask_app):
+    user = create_new_user()
+    with flask_app.test_request_context():
+        login_user(user)
+        sem = threading.Semaphore(0)
+        pl = _InnerLock("test", max_wait_secs=5)
+        t = threading.Thread(target=sleep_thread, args=(pl, sem))
+        t.daemon = True
+        t.start()
+        sem.acquire()
+        try:
+            got_exception = False
+            pl(sleep_thread)(pl)
+        except werkzeug.exceptions.TooManyRequests:
+            got_exception = True
+        assert got_exception