diff --git a/monoid-design.md b/monoid-design.md
index 29f6705a4e8005b072b0d02aad0e67c1933bb384..62689f6dc7b37c17c5e14ceb146d6452e2e8e531 100644
--- a/monoid-design.md
+++ b/monoid-design.md
@@ -173,7 +173,7 @@ Problem: Given a list of numbers, compute their product.
     *   …
 
 *   Monoid:
-    *   `A = (…, …, …)`
+    *   `P = (…, …, …)`
 
 --------------------------------------------------------------------------------
 
@@ -193,7 +193,7 @@ Problem: Given a list of numbers, compute the minimum.
     *   …
 
 *   Monoid:
-    *   `A = (…, …, …)`
+    *   `M = (…, …, …)`
 
 --------------------------------------------------------------------------------