diff --git a/lib/W3/PgCacheFlush.php b/lib/W3/PgCacheFlush.php
index 295fe81..ab7e253 100644
--- a/lib/W3/PgCacheFlush.php
+++ b/lib/W3/PgCacheFlush.php
@@ -44,6 +44,8 @@ function __construct() {
     function flush() {
         $cache = $this->_get_cache();
         w3_minify_version_change();
+        // First, flush the 'sitemaps' group.
+        $cache->flush('sitemaps');
         return $cache->flush();
     }