diff --git a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldDate.php b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldDate.php
--- a/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldDate.php
+++ b/src/infrastructure/customfield/standard/PhabricatorStandardCustomFieldDate.php
@@ -11,7 +11,7 @@
     $indexes = array();
 
     $value = $this->getFieldValue();
-    if (strlen($value)) {
+    if (phutil_nonempty_scalar($value)) {
       $indexes[] = $this->newNumericIndex((int)$value);
     }