diff --git a/zigate/core.py b/zigate/core.py
index 6ceac8ff..0728f410 100644
--- a/zigate/core.py
+++ b/zigate/core.py
@@ -875,6 +875,7 @@ def get_group_membership(self, addr, endpoint, groups=[]):
         '''
         Get group membership
         groups is list of group addr
+        if empty get all groups
         '''
         addr_mode = 2
         addr = self.__addr(addr)