diff --git a/framework/rest/Serializer.php b/framework/rest/Serializer.php
index edc689e94e8..eedd96c2cc6 100644
--- a/framework/rest/Serializer.php
+++ b/framework/rest/Serializer.php
@@ -188,6 +188,12 @@ protected function getRequestedFields()
      */
     protected function serializeDataProvider($dataProvider)
     {
+        if (($pagination = $dataProvider->getPagination()) !== false) {
+            $this->addPaginationHeaders($pagination);
+        }
+        if ($this->request->getIsHead()) {
+            return null;
+        }
         if ($this->preserveKeys) {
             $models = $dataProvider->getModels();
         } else {
@@ -195,13 +201,7 @@ protected function serializeDataProvider($dataProvider)
         }
         $models = $this->serializeModels($models);
 
-        if (($pagination = $dataProvider->getPagination()) !== false) {
-            $this->addPaginationHeaders($pagination);
-        }
-
-        if ($this->request->getIsHead()) {
-            return null;
-        } elseif ($this->collectionEnvelope === null) {
+        if ($this->collectionEnvelope === null) {
             return $models;
         }