diff --git a/tests/common.py b/tests/common.py
index df06dddef..f332b0f66 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -57,7 +57,7 @@
 )
 _pd_ecommerce.insert(2, "customer_birth_date", None)
 _pd_ecommerce.index = _pd_ecommerce.index.map(str)  # make index 'object' not int
-_pd_ecommerce["customer_birth_date"].astype("datetime64")
+_pd_ecommerce["customer_birth_date"].astype("datetime64[ns]")
 _oml_ecommerce = oml.DataFrame(OPENSEARCH_TEST_CLIENT, ECOMMERCE_INDEX_NAME)