diff --git a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldInt.php b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldInt.php
--- a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldInt.php
+++ b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldInt.php
@@ -24,7 +24,8 @@
 
   public function getValueForStorage() {
     $value = $this->getFieldValue();
-    if (strlen($value)) {
+    $is_nonempty = phutil_string_cast($value) !== '';
+    if ($is_nonempty) {
       return $value;
     } else {
       return null;