diff --git a/djaosdb/caosdb_client.py b/djaosdb/caosdb_client.py
index 3b16415163a0d4a95c508a8997c1762206cde0e5..b3cd64384525ca067a194ec7c11bff1faef218ca 100644
--- a/djaosdb/caosdb_client.py
+++ b/djaosdb/caosdb_client.py
@@ -34,6 +34,9 @@ class CountResult(Result):
     def __iter__(self):
         return iter(self._results)
 
+def _sort_key(x, field):
+    return x[field] or ""
+
 class FindResult(Result):
 
     def __init__(self, rows, columns, sort=None, limit=None, skip=None):
@@ -47,7 +50,7 @@ class FindResult(Result):
         if columns is not None:
             if sort:
                 named_columns = [dict(zip(columns, row)) for row in rows]
-                named_columns.sort(key=lambda x: x[sort[0][0]], reverse=sort[0][1] < 0)
+                named_columns.sort(key=lambda x: _sort_key(x, sort[0][0]), reverse=sort[0][1] < 0)
                 self._results = named_columns[skip:upper]
             else:
                 self._results = []