diff --git a/chrome/content/zotero/xpcom/reader.js b/chrome/content/zotero/xpcom/reader.js
index 4ccd7e87a1..a88c204f1b 100644
--- a/chrome/content/zotero/xpcom/reader.js
+++ b/chrome/content/zotero/xpcom/reader.js
@@ -545,34 +545,35 @@ class ReaderInstance {
 		let readerTitle = item.getDisplayTitle();
 		let parentItem = item.parentItem;
 		if (type === 'filename') {
-			let attachment = await parentItem.getBestAttachment();
-			if (attachment && attachment.id === this._item.id) {
-				readerTitle = attachment.attachmentFilename;
-			}
+			readerTitle = item.attachmentFilename;
 		}
 		else if (parentItem) {
-			let attachment = await parentItem.getBestAttachment();
-			if (attachment && attachment.id === this._item.id) {
-				let parts = [];
-				// Windows displays bidi control characters as placeholders in window titles, so strip them
-				// See https://github.com/mozilla-services/screenshots/issues/4863
-				let unformatted = Zotero.isWin;
-				let creator = parentItem.getField('firstCreator', unformatted);
-				let year = parentItem.getField('year');
-				let title = parentItem.getDisplayTitle();
-				// If creator is missing fall back to titleCreatorYear
-				if (type === 'creatorYearTitle' && creator) {
-					parts = [creator, year, title];
-				}
-				else if (type === 'title') {
-					parts = [title];
-				}
-				// If type is titleCreatorYear, or is missing, or another type falls back
-				else {
-					parts = [title, creator, year];
-				}
-				readerTitle = parts.filter(x => x).join(' - ');
+			let parts = [];
+			// Windows displays bidi control characters as placeholders in window titles, so strip them
+			// See https://github.com/mozilla-services/screenshots/issues/4863
+			let unformatted = Zotero.isWin;
+			let creator = parentItem.getField('firstCreator', unformatted);
+			let year = parentItem.getField('year');
+			let title = parentItem.getDisplayTitle();
+			// If creator is missing fall back to titleCreatorYear
+			if (type === 'creatorYearTitle' && creator) {
+				parts = [creator, year, title];
 			}
+			else if (type === 'title') {
+				parts = [title];
+			}
+			// If type is titleCreatorYear, or is missing, or another type falls back
+			else {
+				parts = [title, creator, year];
+			}
+			
+			// If not primary attachment, add attachment title
+			let attachment = await parentItem.getBestAttachment();
+			if (!attachment || attachment.id != item.id) {
+				parts.unshift(item.getDisplayTitle());
+			}
+			
+			readerTitle = parts.filter(Boolean).join(' - ');
 		}
 		this._title = readerTitle;
 		this._setTitleValue(readerTitle);