diff --git a/typo3/sysext/backend/Configuration/ContentSecurityPolicies.php b/typo3/sysext/backend/Configuration/ContentSecurityPolicies.php
index 3a57b2ed4b..8e8fce1450 100644
--- a/typo3/sysext/backend/Configuration/ContentSecurityPolicies.php
+++ b/typo3/sysext/backend/Configuration/ContentSecurityPolicies.php
@@ -24,7 +24,7 @@ return Map::fromEntries([
         new Mutation(MutationMode::Extend, Directive::ScriptSrc, SourceKeyword::nonceProxy),
         // `style-src 'unsafe-inline'` required for lit in safari and firefox to allow inline <style> tags
         // (for browsers that do not support https://caniuse.com/mdn-api_shadowroot_adoptedstylesheets)
-        new Mutation(MutationMode::Extend, Directive::StyleSrc, SourceKeyword::unsafeInline),
+        new Mutation(MutationMode::Extend, Directive::StyleSrc, SourceKeyword::unsafeInline, SourceKeyword::nonceProxy),
         // `style-src-attr 'unsafe-inline'` required for remaining inline styles, which is okay for color & dimension
         // (e.g. `<div style="color: #000">` - but NOT having the possibility to use any other assets/files/URIs)
         new Mutation(MutationMode::Set, Directive::StyleSrcAttr, SourceKeyword::unsafeInline),