diff --git a/Tests/test_decompression_bomb.py b/Tests/test_decompression_bomb.py
index 132269933..7671cdc09 100644
--- a/Tests/test_decompression_bomb.py
+++ b/Tests/test_decompression_bomb.py
@@ -11,7 +11,7 @@ ORIGINAL_LIMIT = Image.MAX_IMAGE_PIXELS
 
 class TestDecompressionBomb:
     @classmethod
-    def teardown_class(self):
+    def teardown_class(cls):
         Image.MAX_IMAGE_PIXELS = ORIGINAL_LIMIT
 
     def test_no_warning_small_file(self):