diff --git a/pantheon.upstream.yml b/pantheon.upstream.yml
index f44355bd..7c2d1219 100644
--- a/pantheon.upstream.yml
+++ b/pantheon.upstream.yml
@@ -2,7 +2,7 @@ api_version: 1
 web_docroot: true
 # See https://pantheon.io/docs/pantheon-yml/#enforce-https--hsts for valid values.
 enforce_https: transitional
-php_version: 7.4
+php_version: 8.1
 database:
   version: 10.4
 build_step: true