diff --git a/code/ddns-lambda.py b/code/ddns-lambda.py
index c2b132a..96c3d01 100755
--- a/code/ddns-lambda.py
+++ b/code/ddns-lambda.py
@@ -746,7 +746,7 @@ def lambda_handler(
             f"5.1 instance: {instance_id}, PTR using tag_option.ptrname hostname {tag_data['option_ptrname'].hostname} and tag_option.ptrname zone {tag_data['option_ptrname'].zonename}")
         p_hostname = tag_data['option_ptrname'].hostname
         p_zonename = tag_data['option_ptrname'].zonename
-    elif tag_data['option_ptrname'].exists:
+    elif tag_data['option_ptrname'].defined:
         LOGGER.info(
             f"5.2 instance: {instance_id}, PTR using name not-valid, forcing tag_option.ptrname hostname {tag_data['option_ptrname'].hostname} and tag_option.ptrname zone {tag_data['option_ptrname'].zonename}")
         p_hostname = tag_data['option_ptrname'].hostname