diff --git a/core/audits/seo/robots-txt.js b/core/audits/seo/robots-txt.js
index 7176c473d643..19450c88b64e 100644
--- a/core/audits/seo/robots-txt.js
+++ b/core/audits/seo/robots-txt.js
@@ -27,7 +27,7 @@ const DIRECTIVE_SAFELIST = new Set([
   DIRECTIVE_ALLOW, DIRECTIVE_SITEMAP, // universally supported
   'crawl-delay', // yahoo, bing, yandex
   'clean-param', 'host', // yandex
-  'request-rate', 'visit-time', 'noindex', // not officially supported, but used in the wild
+  'request-rate', 'visit-time', 'noindex', 'content-signal', // not officially supported, but used in the wild
 ]);
 const SITEMAP_VALID_PROTOCOLS = new Set(['https:', 'http:', 'ftp:']);
 
diff --git a/core/test/audits/seo/robots-txt-test.js b/core/test/audits/seo/robots-txt-test.js
index 7de1fa59816c..73a3676bd891 100644
--- a/core/test/audits/seo/robots-txt-test.js
+++ b/core/test/audits/seo/robots-txt-test.js
@@ -224,6 +224,9 @@ User-agent: NotOfficial
 noindex: /bla
 Visit-time: 0600-0845
 Request-rate: 1/30m
+
+User-agent: RespectfulAI
+Content-Signal: ai-train=yes, search=yes, ai-input=yes
 `,
       },
     ];