diff --git a/dpdata/system.py b/dpdata/system.py
index 44440a714..f4399a02b 100644
--- a/dpdata/system.py
+++ b/dpdata/system.py
@@ -162,7 +162,7 @@ def __str__(self):
 
     def __getitem__(self, key):
         """Returns proerty stored in System by key or by idx"""
-        if isinstance(key, int):
+        if isinstance(key, (int, slice)):
             return self.sub_system(key)
         return self.data[key]