diff --git a/_posts/2022-12-10-why-be-pure.md b/_posts/2022-12-10-why-be-pure.md
index f424382..ce0e576 100644
--- a/_posts/2022-12-10-why-be-pure.md
+++ b/_posts/2022-12-10-why-be-pure.md
@@ -17,6 +17,7 @@ Before we get into the why, we have to get into the what. Haskell is a purely fu
 n = 0
 
 def f(x):
+  global n
   n = n + x
   return n
 ```