diff --git a/lib/components/user/notification-prefs-pane.js b/lib/components/user/notification-prefs-pane.js
index <HASH>..<HASH> 100644
--- a/lib/components/user/notification-prefs-pane.js
+++ b/lib/components/user/notification-prefs-pane.js
@@ -368,6 +368,7 @@ class PhoneNumberEditor extends Component {
             <p>
               Please check the SMS messaging app on your mobile phone
               for a text message with a verification code, and enter the code below.
+              The verification code expires after 10 minutes.
             </p>
             <ControlLabel>Verification code:</ControlLabel>
             <ControlStrip>
refactor(PhoneNumberEditor): Mention code expiration in SMS instructions.