diff --git a/apis/python/src/tiledbsoma/io/_registration/ambient_label_mappings.py b/apis/python/src/tiledbsoma/io/_registration/ambient_label_mappings.py
index e12d971891..bb619fc870 100644
--- a/apis/python/src/tiledbsoma/io/_registration/ambient_label_mappings.py
+++ b/apis/python/src/tiledbsoma/io/_registration/ambient_label_mappings.py
@@ -350,7 +350,7 @@ def _acquire_experiment_mappings(
         """Acquires label-to-ID mappings from the baseline, already-written SOMA experiment."""
 
         if experiment_uri is not None:
-            if not tiledbsoma.Experiment.exists(experiment_uri):
+            if not tiledbsoma.Experiment.exists(experiment_uri, context=context):
                 raise ValueError("cannot find experiment at URI {experiment_uri}")
 
             # Pre-check