diff --git a/customize/third-party-libraries.mdx b/customize/third-party-libraries.mdx
index 9419eccde..c836e73cf 100644
--- a/customize/third-party-libraries.mdx
+++ b/customize/third-party-libraries.mdx
@@ -14,7 +14,9 @@ Use components from npm packages, such as charts or your own design system, in y
   Only install packages you trust. Package code runs with the same access as the page, including the page content and anything the reader's browser stores for your site. It can make network requests to any server. Removing a package or rolling back a deployment doesn't stop code that already loaded in a reader's browser.
 </Warning>
 
-Third-party libraries aren't available on sites that use [authentication](/deploy/authentication-setup) or [personalization](/create/personalization). Deployments that include `packages` in `docs.json` fail on those sites.
+Third-party libraries aren't available on sites that use [authentication](/deploy/authentication-setup) or [personalization](/create/personalization). Deployments that include `packages` in `docs.json` fail on those sites. This also applies to [preview deployments](/deploy/preview-deployments#restrict-access-to-preview-deployments) that require organization authentication or a password.
+
+While your site uses third-party libraries, you can't turn on authentication, personalization, or access restrictions for preview deployments.
 
 ## Add a package