diff --git a/classes/deck/deck_holder.gd b/classes/deck/deck_holder.gd
index c1210cb..6b32cd2 100644
--- a/classes/deck/deck_holder.gd
+++ b/classes/deck/deck_holder.gd
@@ -272,25 +272,27 @@ static func close_deck(deck_id: String) -> Array:
 
 
 static func pre_exit_cleanup() -> void:
-	for deck_id: String in decks:
+	for deck_id: String in decks.keys():
 		if decks[deck_id] is Deck:
 			var deck: Deck = decks[deck_id]
 			print_verbose("DeckHolder: freeing deck %s, id %s" % [deck.id, deck.get_instance_id()])
 			deck.pre_exit_cleanup()
 			deck.free()
 		else:
-			for instance_id: String in decks[deck_id]:
+			for instance_id: String in (decks[deck_id] as Dictionary).keys():
 				var deck: Deck = decks[deck_id][instance_id]
 				print_verbose("DeckHolder: freeing group %s::%s, id %s" % [deck_id, instance_id, deck.get_instance_id()])
 				deck.pre_exit_cleanup()
 				deck.free()
+		decks.erase(deck_id)
 	
-	for lib_id: String in lib_groups:
+	for lib_id: String in lib_groups.keys():
 		for instance_id: String in lib_groups[lib_id]:
 			var deck: Deck = lib_groups[lib_id][instance_id]
 			print_verbose("DeckHolder: freeing lib group %s::%s, id %s" % [lib_id, instance_id, deck.get_instance_id()])
 			deck.pre_exit_cleanup()
 			deck.free()
+		lib_groups.erase(lib_id)
 
 
 static func send_event(event_name: StringName, event_data: Dictionary = {}) -> void: