diff --git a/pybigquery/sqlalchemy_bigquery.py b/pybigquery/sqlalchemy_bigquery.py
index 6fc047e1..204936d1 100644
--- a/pybigquery/sqlalchemy_bigquery.py
+++ b/pybigquery/sqlalchemy_bigquery.py
@@ -606,7 +606,7 @@ def create_connect_args(self, url):
             list_tables_page_size
         ) = parse_url(url)
 
-        self.arraysize = self.arraysize or arraysize
+        self.arraysize = arraysize or self.arraysize
         self.list_tables_page_size = list_tables_page_size or self.list_tables_page_size
         self.location = location or self.location
         self.credentials_path = credentials_path or self.credentials_path