diff --git a/chapters/requirements.bd b/chapters/requirements.bd
index 9ad3e2a..a5d8487 100644
--- a/chapters/requirements.bd
+++ b/chapters/requirements.bd
@@ -16,11 +16,11 @@ There are some approaches to specifying requirements _formally_. These technique
 
 Expressing requirements in natural language can mitigate these effects, at the expense of precision. They just have to be *complete*, *precise*, *non-conflicting*, and *verifiable*. For example, consider a design for a simple to do list application. It's requirements might be something like the following:
 		
-* Users should be able to add to-do list items with a single click.
+* Users must be able to add to-do list items with a single action.
 * To-do list items must contain text and a binary completed state.
-* Users should be able to edit the text of to-do list items.
-* Users should be able to toggle the completed state of to-do list items.
-* Users should be able to delete to-do list items.
+* Users must be able to edit the text of to-do list items.
+* Users must be able to toggle the completed state of to-do list items.
+* Users must be able to delete to-do list items.
 * All changes made to the state of to-do list items must be saved automatically without user intervention.
 		
 Let's review these requirements against the criteria for good requirements that I listed above: