diff --git a/presto/auth.py b/presto/auth.py
index 02a30d04..ddb754b8 100644
--- a/presto/auth.py
+++ b/presto/auth.py
@@ -85,7 +85,7 @@ def set_http_session(self, http_session):
             delegate=self._delegate,
             service=self._service_name,
         )
-        if self._ca_bundle:
+        if self._ca_bundle is not None:
             http_session.verify = self._ca_bundle
         return http_session