diff --git a/gpiozero/boards.py b/gpiozero/boards.py
index a962e64..27d6b4c 100644
--- a/gpiozero/boards.py
+++ b/gpiozero/boards.py
@@ -580,7 +580,7 @@ class XmasTree(LEDBoard):
 
         tree.star.on()
 
-        for bauble in tree.baubles:
+        for bauble in tree.baubles.values():
             bauble.source_delay = 0.1
             bauble.source = random_values()