diff --git a/src/PIL/BlpImagePlugin.py b/src/PIL/BlpImagePlugin.py
index 355795cb9..ab09b552c 100644
--- a/src/PIL/BlpImagePlugin.py
+++ b/src/PIL/BlpImagePlugin.py
@@ -40,10 +40,6 @@ from typing import IO
 
 from . import Image, ImageFile
 
-branches = {
-            "1": False,
-            "2": False,
-    }
 
 class Format(IntEnum):
     JPEG = 0
@@ -290,11 +286,11 @@ class _BLPBaseDecoder(ImageFile.PyDecoder):
 
     def decode(self, buffer: bytes) -> tuple[int, int]:
         try:
-            branches["1"] = True
+            _BLPBaseDecoder.branches["1"] = True
             self._read_blp_header()
             self._load()
         except struct.error as e:
-            branches["2"] = True
+            _BLPBaseDecoder.branches["2"] = True
             msg = "Truncated BLP file"
             raise OSError(msg) from e
         return -1, 0