diff --git a/includes/Wpup/Package.php b/includes/Wpup/Package.php
index 36c5840..8d4617c 100644
--- a/includes/Wpup/Package.php
+++ b/includes/Wpup/Package.php
@@ -68,7 +68,7 @@ public function getMetadata() {
 	 */
 	public static function fromArchive($filename, $slug = null, Wpup_Cache $cache = null) {
 		$modified = filemtime($filename);
-		$cacheKey = 'metadata-' . $slug . '-' . md5($filename . '|' . filesize($filename) . '|' . $modified);
+		$cacheKey = 'metadata-b64-' . $slug . '-' . md5($filename . '|' . filesize($filename) . '|' . $modified);
 		$metadata = null;
 
 		//Try the cache first.