diff --git a/book/stacks/postfix_evaluation.py b/book/stacks/postfix_evaluation.py
index bb123d3f..d2676735 100644
--- a/book/stacks/postfix_evaluation.py
+++ b/book/stacks/postfix_evaluation.py
@@ -2,7 +2,7 @@
 
 OPERATION = {
     '*': operator.mul,
-    '/': operator.div,
+    '/': operator.truediv,
     '-': operator.sub,
     '+': operator.add
 }