diff --git a/tosfs/tests/test_fsspec_integration.py b/tosfs/tests/test_fsspec_integration.py
index d4ce00d..fc08055 100644
--- a/tosfs/tests/test_fsspec_integration.py
+++ b/tosfs/tests/test_fsspec_integration.py
@@ -95,6 +95,9 @@ def test_customized_class(bucket, temporary_workspace):
     )
 
     logger.error("----------------")
+    logger.error("tos" in fsspec.registry)
+    logger.error(fsspec.registry["tos"])
+    logger.error(fsspec.registry.known_implementations["tos"])
     logger.error(fsspec.get_filesystem_class("tos"))
 
     file = f"{random_str()}.txt"