diff --git a/docs/layout/grid.md b/docs/layout/grid.md
index 95fd999f36..ca3537e843 100644
--- a/docs/layout/grid.md
+++ b/docs/layout/grid.md
@@ -710,10 +710,11 @@ $grid-gutter-widths: (
 
 ### Grid tiers
 
-Moving beyond the columns themselves, you may also customize the number of grid tiers. If you wanted just three grid tiers, you'd update the `$grid-breakpoints` and `$container-max-widths` to something like this:
+Moving beyond the columns themselves, you may also customize the number of grid tiers. If you wanted just four grid tiers, you'd update the `$grid-breakpoints` and `$container-max-widths` to something like this:
 
 {% highlight scss %}
 $grid-breakpoints: (
+  xs: 0,
   sm: 480px,
   md: 768px,
   lg: 1024px