diff --git a/u2/list_ops.py b/u2/list_ops.py
index 5f19ccb..fe1b916 100644
--- a/u2/list_ops.py
+++ b/u2/list_ops.py
@@ -40,7 +40,7 @@ def foldl(function, list, initial):
 def foldr(function, list, initial):
     acc = initial
     for gns in list[::-1]:
-        acc = function(gns, acc)
+        acc = function(acc, gns)
     return acc
 
 def reverse(list):