diff --git a/Tests/test_file_bufrstub.py b/Tests/test_file_bufrstub.py
index 77ee5b0ea..fc8920317 100644
--- a/Tests/test_file_bufrstub.py
+++ b/Tests/test_file_bufrstub.py
@@ -83,4 +83,4 @@ def test_handler(tmp_path: Path) -> None:
         im.save(temp_file)
         assert handler.saved
 
-    BufrStubImagePlugin._handler = None
+    BufrStubImagePlugin.register_handler(None)
diff --git a/Tests/test_file_gribstub.py b/Tests/test_file_gribstub.py
index aba473d24..02e464ff1 100644
--- a/Tests/test_file_gribstub.py
+++ b/Tests/test_file_gribstub.py
@@ -83,4 +83,4 @@ def test_handler(tmp_path: Path) -> None:
         im.save(temp_file)
         assert handler.saved
 
-    GribStubImagePlugin._handler = None
+    GribStubImagePlugin.register_handler(None)
diff --git a/Tests/test_file_hdf5stub.py b/Tests/test_file_hdf5stub.py
index 8275bd0d8..024be9e80 100644
--- a/Tests/test_file_hdf5stub.py
+++ b/Tests/test_file_hdf5stub.py
@@ -85,4 +85,4 @@ def test_handler(tmp_path: Path) -> None:
         im.save(temp_file)
         assert handler.saved
 
-    Hdf5StubImagePlugin._handler = None
+    Hdf5StubImagePlugin.register_handler(None)