diff --git a/src/fix.py b/src/fix.py
index bc44244f4..87b679bdf 100644
--- a/src/fix.py
+++ b/src/fix.py
@@ -53,11 +53,14 @@ def choice(iterable):
         return _choice(iterable)
     else:
         n = 1
-        ret = None
+        m = new.module('') # Guaranteed unique value.
+        ret = m
         for x in iterable:
             if random.random() < 1/n:
                 ret = x
             n += 1
+        if ret is m:
+            raise IndexError
         return ret
 random.choice = choice