diff --git a/src/apify/_utils.py b/src/apify/_utils.py
index 38e9a66e..23a75e67 100644
--- a/src/apify/_utils.py
+++ b/src/apify/_utils.py
@@ -141,6 +141,8 @@ def __init__(self) -> None:
     async def __call__(self) -> AsyncIterator[None]:
         """Acquire the lock if it's not already owned by the current task, otherwise proceed without acquiring."""
         me = asyncio.current_task()
+        if me is None:
+            raise RuntimeError('ReentrantLock must be used within an asyncio.Task')
         if self._owner is me:
             yield
             return