diff --git a/tosfs/tests/test_fsspec_integration.py b/tosfs/tests/test_fsspec_integration.py
index 6a3e189..ea92f7c 100644
--- a/tosfs/tests/test_fsspec_integration.py
+++ b/tosfs/tests/test_fsspec_integration.py
@@ -93,11 +93,13 @@ def test_customized_class(bucket, temporary_workspace):
     fsspec.register_implementation(
         "tos", "tosfs.tests.test_fsspec_integration.MyTosFileSystem", True
     )
-    fsspec.registry["tos"] = "tosfs.tests.test_fsspec_integration.MyTosFileSystem"
+    fsspec._registry = "tosfs.tests.test_fsspec_integration.MyTosFileSystem"
 
     logger.error("----------------")
     logger.error("tos" in fsspec.registry)
     logger.error(f"fsspec.registry {fsspec.registry}")
+    logger.error(known_implementations)
+    logger.error(known_implementations["tos"])
     logger.error(fsspec.get_filesystem_class("tos"))
 
     file = f"{random_str()}.txt"