diff --git a/oml/queryparser.py b/oml/queryparser.py
index 8562218..2091fb2 100644
--- a/oml/queryparser.py
+++ b/oml/queryparser.py
@@ -2,6 +2,7 @@
 
 from datetime import datetime
 import unicodedata
+import sqlalchemy.orm.exc
 from sqlalchemy.sql import operators
 from sqlalchemy.orm import load_only
 from sqlalchemy.sql.expression import text