diff -u b/date_api/date_api.module b/date_api/date_api.module
--- b/date_api/date_api.module
+++ b/date_api/date_api.module
@@ -660,7 +660,7 @@
           $final_date['month'] = intval($value);
           $this->addGranularity('month');
           if (empty($value)) {
-            $this->erros['month'] = t('The month is invalid.');
+            $this->errors['month'] = t('The month is invalid.');
           }
           break;