diff --git a/CRM/TwingleCampaign/Upgrader/BAO/CustomField.php b/CRM/TwingleCampaign/Upgrader/BAO/CustomField.php
index a775d8c..68c2c51 100644
--- a/CRM/TwingleCampaign/Upgrader/BAO/CustomField.php
+++ b/CRM/TwingleCampaign/Upgrader/BAO/CustomField.php
@@ -230,7 +230,9 @@ class CustomField {
     $customFieldMapping = [];
 
     foreach ($customFields as $customField) {
-      $customFieldMapping[$customField->getName()] = 'custom_' . $customField->getId();
+      if ($customField) {
+        $customFieldMapping[$customField->getName()] = 'custom_' . $customField->getId();
+      }
     }
 
     return $customFieldMapping;