diff --git a/config/system/additional.php b/config/system/additional.php
index 8f646c6..ac619f2 100644
--- a/config/system/additional.php
+++ b/config/system/additional.php
@@ -94,6 +94,10 @@ $GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['rootline']
 ];
 unset($redisOptions);
 
+// Favicon sets from realfavicongenerator.net (fileadmin/user_upload/favicon/<site>/) contain an ICO
+// and a web manifest, which TYPO3 13 rejects on upload unless an extension list allows them
+$GLOBALS['TYPO3_CONF_VARS']['SYS']['miscfile_ext'] .= ',ico,webmanifest';
+
 // Deployer creates an empty secrets.php if none exists yet: only an array counts
 $secrets = is_file(__DIR__ . '/secrets.php') ? require __DIR__ . '/secrets.php' : null;
 if (is_array($secrets)) {