diff --git a/requirements.txt b/requirements.txt
index 3093f74..410c921 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,4 +2,5 @@ fastmcp[http]==3.2.0
 boto3==1.38.13
 gitpython==3.1.44
 prometheus_client==0.22.1
+requests>=2.31
 watchdog==6.0.0
diff --git a/src/caching.py b/src/caching.py
index af2e2ae..e764b49 100644
--- a/src/caching.py
+++ b/src/caching.py
@@ -53,7 +53,10 @@ def _get_cached(tool_name: str, key: str, ttl: float) -> tuple[bool, object]:
     if tool_name not in _caches:
         return (False, None)
 
-    with _locks.get(tool_name, threading.Lock()):
+    if tool_name not in _locks:
+        _locks[tool_name] = threading.Lock()
+
+    with _locks[tool_name]:
         entry = _caches[tool_name].get(key)
         if entry is None:
             return (False, None)