diff --git a/netbox/utilities/utils.py b/netbox/utilities/utils.py
index 45fbf1c7c..14c29d211 100644
--- a/netbox/utilities/utils.py
+++ b/netbox/utilities/utils.py
@@ -97,7 +97,7 @@ def serialize_object(obj, extra=None):
     # Include any custom fields
     if hasattr(obj, 'get_custom_fields'):
         data['custom_fields'] = {
-            field.name: value for field, value in obj.get_custom_fields().items()
+            field.name: str(value) for field, value in obj.get_custom_fields().items()
         }
 
     # Include any tags