diff --git a/buggy.py b/buggy.py
--- a/buggy.py
+++ b/buggy.py
@@ -15,6 +15,6 @@
         d[0] = 0
         d[1] = d[2] = 1
         for i in range(3, n + 1):
-            d.append(sum(d[1:]))
+            d.append(sum(d))
             d.pop(0)
         return d[2]
