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
@@ -84,7 +84,7 @@
 
     foreach ($xactions as $xaction) {
       $value = $xaction->getNewValue();
-      if (strlen($value)) {
+      if ($value !== null) {
         if (!preg_match('/^-?\d+/', $value)) {
           $errors[] = new PhabricatorApplicationTransactionValidationError(
             $type,
@@ -104,9 +104,9 @@
 
     $old = $xaction->getOldValue();
     $new = $xaction->getNewValue();
-    if (!strlen($old) && strlen($new)) {
+    if ($old === null && $new !== null) {
       return true;
-    } else if (strlen($old) && !strlen($new)) {
+    } else if ($old !== null  && $new === null) {
       return true;
     } else {
       return ((int)$old !== (int)$new);