diff --git a/warrant/__init__.py b/warrant/__init__.py
index c715cd7c..4ba09945 100644
--- a/warrant/__init__.py
+++ b/warrant/__init__.py
@@ -162,7 +162,7 @@ def __init__(
 
         boto3_client_kwargs = {}
         if access_key and secret_key:
-            boto3_client_kwargs['aws_access_key'] = access_key
+            boto3_client_kwargs['aws_access_key_id'] = access_key
             boto3_client_kwargs['aws_secret_access_key'] = secret_key
         if user_pool_region:
             boto3_client_kwargs['region_name'] = user_pool_region