diff --git a/zulip/zulip/__init__.py b/zulip/zulip/__init__.py
index 4b4829367..1d0b81311 100644
--- a/zulip/zulip/__init__.py
+++ b/zulip/zulip/__init__.py
@@ -489,7 +489,7 @@ def __init__(
             )
             self.tls_verification = False  # type: Union[bool, str]
         elif cert_bundle is not None:
-            if not os.path.isfile(cert_bundle):
+            if not os.path.exists(cert_bundle):
                 raise ConfigNotFoundError(f"tls bundle '{cert_bundle}' does not exist")
             self.tls_verification = cert_bundle
         else: