diff --git a/framework/filters/HttpCache.php b/framework/filters/HttpCache.php
index 0f37870b97..5420c25e67 100644
--- a/framework/filters/HttpCache.php
+++ b/framework/filters/HttpCache.php
@@ -188,6 +188,6 @@ class HttpCache extends ActionFilter
      */
     protected function generateEtag($seed)
     {
-        return '"' . base64_encode(sha1($seed, true)) . '"';
+        return '"' . rtrim(base64_encode(sha1($seed, true)), '=') . '"';
     }
 }