From 366635110fa91d2ff90e6547c5c64ef0c4a19038 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Sat, 28 Dec 2024 12:14:30 +1100
Subject: [PATCH] check

---
 src/PIL/Jpeg2KImagePlugin.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/PIL/Jpeg2KImagePlugin.py b/src/PIL/Jpeg2KImagePlugin.py
index b6ebd562be6..79452a63af0 100644
--- a/src/PIL/Jpeg2KImagePlugin.py
+++ b/src/PIL/Jpeg2KImagePlugin.py
@@ -266,6 +266,8 @@ def _open(self) -> None:
             else:
                 msg = "not a JPEG 2000 file"
                 raise SyntaxError(msg)
+        if self.mode == "CMYK":
+            assert False
 
         self._reduce = 0
         self.layers = 0