diff -u b/src/Query/Query.php b/src/Query/Query.php
--- b/src/Query/Query.php
+++ b/src/Query/Query.php
@@ -319,6 +319,11 @@
     if (!$this->preExecuteRan) {
       $this->preExecuteRan = TRUE;
 
+      // Add fulltext fields, unless set
+      if ($this->fields === NULL) {
+        $this->fields = $this->index->getFulltextFields();
+      }
+
       // Preprocess query.
       $this->index->preprocessSearchQuery($this);