diff --git a/biothings_client/base.py b/biothings_client/base.py
index 7e8acb5..593200f 100644
--- a/biothings_client/base.py
+++ b/biothings_client/base.py
@@ -392,6 +392,10 @@ def _getannotations(self, ids, fields=None, **kwargs):
         .. Hint:: If you need to pass a very large list of input ids, you can pass a generator
                   instead of a full list, which is more memory efficient.
         """
+        if isinstance(ids, str_types):
+            ids = ids.split(",") if ids else []
+        if not (isinstance(ids, (list, tuple, Iterable))):
+            raise ValueError('input "ids" must be a list, tuple or iterable.')
         if fields:
             kwargs["fields"] = fields
         kwargs = self._handle_common_kwargs(kwargs)