diff --git a/src/utils/PhutilBufferedIterator.php b/src/utils/PhutilBufferedIterator.php
--- a/src/utils/PhutilBufferedIterator.php
+++ b/src/utils/PhutilBufferedIterator.php
@@ -89,7 +89,7 @@
    * @task iterator
    */
   final public function valid() {
-    return (bool)$this->data;
+    return (bool)count($this->data);
   }