diff --git a/src/async_examples/concurrency.py b/src/async_examples/concurrency.py
index 9f1ca66..ba339a5 100644
--- a/src/async_examples/concurrency.py
+++ b/src/async_examples/concurrency.py
@@ -19,6 +19,8 @@ async def some_api_call(urls):
 
 
 async def retry_with_backoff(func, max_retries=3):
+    if max_retries < 1:
+        raise ValueError("max_retries must be at least 1")
     last_exception = None
     for attempt in range(max_retries):
         try:
@@ -44,5 +46,5 @@ async def sorter(arr):
 
 
 async def task():
-    time.sleep(1)
-    return "done"
\ No newline at end of file
+    await asyncio.sleep(0.00001)
+    return "done"