diff --git a/TailRecursion.py b/TailRecursion.py
index 75a26fe3638ac61dba9fe10c3d6823ed48211acf..90c8121252d63f9bab35087f781d1eeb83c2d1a0 100755
--- a/TailRecursion.py
+++ b/TailRecursion.py
@@ -10,7 +10,7 @@ def slightly_better_iterator(a_list):
 
 
 def poorly_defined_adder(a_list):
-    if len(a_list == 0):
+    if len(a_list) == 0:
         return 0
     else:
         return a_list[0] + poorly_defined_adder(a_list[1:])