diff --git a/CHANGELOG.md b/CHANGELOG.md
index 845a90a..8e8f105 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -86,3 +86,4 @@ List of changes since the fork of Apprentice Harper's repository:
 - Obok: Add new setting option "Add new entry" for duplicate books to always add them to the Calibre database as a new book. Fixes #148.
 - Obok: Fix where changing the Calibre UI language to some languages would cause the "duplicate book" setting to reset.
 - Fix Python3 bug in stylexml2css.php script, fixes #232.
+- PDF: Ignore invalid PDF objids unless the script is running in strict mode. Fixes some PDFs, apparently. Fixes #233.