diff --git a/packages/rocketchat-lib/server/models/Subscriptions.coffee b/packages/rocketchat-lib/server/models/Subscriptions.coffee
index 527cc7e7cb0..8180095015e 100644
--- a/packages/rocketchat-lib/server/models/Subscriptions.coffee
+++ b/packages/rocketchat-lib/server/models/Subscriptions.coffee
@@ -8,6 +8,7 @@ RocketChat.models.Subscriptions = new class extends RocketChat.models._Base
 		@tryEnsureIndex { 'alert': 1 }
 		@tryEnsureIndex { 'unread': 1 }
 		@tryEnsureIndex { 'ts': 1 }
+		@tryEnsureIndex { 'ls': 1 }
 
 
 	# FIND ONE