diff --git a/geomagio/processing/copy_absolutes.py b/geomagio/processing/copy_absolutes.py
index a438c24644c71663829e92deb269181485578901..2addce461f9d35e7b4679f88dab0f232ea814f97 100644
--- a/geomagio/processing/copy_absolutes.py
+++ b/geomagio/processing/copy_absolutes.py
@@ -116,7 +116,7 @@ def create_reading_metadata(reading: Reading, created_by_label: str) -> Metadata
             category=MetadataCategory.READING,
             created_by=(created_by_label),
             endtime=max(measurement_times),
-            metadata=json.loads(reading.json()),
+            metadata=json.loads(reading.model_dump_json()),
             network="NT",
             starttime=min(measurement_times),
             station=reading.metadata["station"],