diff --git a/SECURITY.md b/SECURITY.md
index 6f4c08c..91f891f 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -30,6 +30,9 @@ coordinate a fix and disclosure with you.
 
 If you used AI tooling to find or write up the report, please say so.
 
+**We do not accept PDF files.** Write the report as plain text or Markdown in
+the advisory or email body, and attach code or logs as text files.
+
 ## Our commitment (safe harbor)
 
 We consider security research conducted in good faith under this policy to be