diff --git a/docs/class.md b/docs/class.md
index a235dd6..5d8b2e9 100644
--- a/docs/class.md
+++ b/docs/class.md
@@ -975,7 +975,7 @@ class Rectangle {
 }
 
 class Square extends Rectangle {
-  constructor(length) {
+  constructor(length, width) {
     super(length, width);
   }
 }