diff --git a/chrome/content/zotero/xpcom/pdfWorker/manager.js b/chrome/content/zotero/xpcom/pdfWorker/manager.js
index 650407731a..598bc0176e 100644
--- a/chrome/content/zotero/xpcom/pdfWorker/manager.js
+++ b/chrome/content/zotero/xpcom/pdfWorker/manager.js
@@ -105,7 +105,7 @@ class PDFWorker {
 							{ responseType: 'arraybuffer' }
 						);
 						respData = {
-							compressionType: 1,
+							isCompressed: true,
 							cMapData: new Uint8Array(response.response)
 						};
 					}