diff --git a/chrome/content/zotero/xpcom/data/item.js b/chrome/content/zotero/xpcom/data/item.js
index 6b8c256b05..c37de5900b 100644
--- a/chrome/content/zotero/xpcom/data/item.js
+++ b/chrome/content/zotero/xpcom/data/item.js
@@ -3962,23 +3962,14 @@ Zotero.Item.prototype.getAnnotations = function (includeTrashed) {
  * Determine if the item is a PDF attachment that exists on disk and contains
  * embedded markup annotations.
  *
- * @return {Promise<Boolean>}
+ * @return {Promise<Boolean>} Rejects if file does not exist on disk
  */
 Zotero.Item.prototype.hasEmbeddedAnnotations = async function () {
 	if (!this.isPDFAttachment()) {
 		return false;
 	}
 
-	let path = await this.getFilePathAsync();
-	if (!path) {
-		return false;
-	}
-
-	let contents = await Zotero.File.getContentsAsync(path);
-	// Check for "markup" annotations per the PDF spec
-	// https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/PDF32000_2008.pdf, p. 390
-	let re = /\/Subtype\s*\/(Text|FreeText|Line|Square|Circle|Polygon|PolyLine|Highlight|Underline|Squiggly|StrikeOut|Stamp|Caret|Ink|FileAttachment|Sound|Redact)/;
-	return re.test(contents);
+	return Zotero.PDFWorker.hasAnnotations(this.id, true);
 };
 
 
diff --git a/chrome/content/zotero/xpcom/data/items.js b/chrome/content/zotero/xpcom/data/items.js
index de59e35a04..e3c25bada5 100644
--- a/chrome/content/zotero/xpcom/data/items.js
+++ b/chrome/content/zotero/xpcom/data/items.js
@@ -1151,9 +1151,15 @@ Zotero.Items = function() {
 				}
 
 				// Check whether master and other have embedded annotations
-				if (await otherAttachment.hasEmbeddedAnnotations()) {
+				// Error -> be safe and assume the item does have embedded annotations
+				let logAndBeSafe = (e) => {
+					Zotero.logError(e);
+					return true;
+				};
+
+				if (await otherAttachment.hasEmbeddedAnnotations().catch(logAndBeSafe)) {
 					// Other yes, master yes -> keep both
-					if (await masterAttachment.hasEmbeddedAnnotations()) {
+					if (await masterAttachment.hasEmbeddedAnnotations().catch(logAndBeSafe)) {
 						Zotero.debug(`Master attachment ${masterAttachment.key} matches ${otherAttachment.key}, `
 							+ 'but both have embedded annotations - keeping both');
 						otherAttachment.parentItemID = item.id;
diff --git a/chrome/content/zotero/xpcom/pdfWorker/manager.js b/chrome/content/zotero/xpcom/pdfWorker/manager.js
index a99b3100d9..c593d8266c 100644
--- a/chrome/content/zotero/xpcom/pdfWorker/manager.js
+++ b/chrome/content/zotero/xpcom/pdfWorker/manager.js
@@ -684,6 +684,47 @@ class PDFWorker {
 			return result;
 		}, isPriority);
 	}
+
+	/**
+	 * Determine whether the PDF has any embedded annotations
+	 *
+	 * @param {Integer} itemID Attachment item id
+	 * @param {Boolean} [isPriority]
+	 * @param {String} [password]
+	 * @returns {Promise<Boolean>}
+	 */
+	async hasAnnotations(itemID, isPriority, password) {
+		return this._enqueue(async () => {
+			let attachment = await Zotero.Items.getAsync(itemID);
+
+			Zotero.debug(`Detecting embedded annotations in item ${attachment.libraryKey}`);
+
+			if (!attachment.isPDFAttachment()) {
+				throw new Error('Item must be a PDF attachment');
+			}
+
+			let path = await attachment.getFilePathAsync();
+			let buf = await OS.File.read(path, {});
+			buf = new Uint8Array(buf).buffer;
+
+			try {
+				var result = await this._query('hasAnnotations', { buf, password }, [buf]);
+			}
+			catch (e) {
+				let error = new Error(`Worker 'hasAnnotations' failed: ${JSON.stringify({ error: e.message })}`);
+				try {
+					error.name = JSON.parse(e.message).name;
+				}
+				catch (e) {
+					Zotero.logError(e);
+				}
+				Zotero.logError(error);
+				throw error;
+			}
+
+			return result.hasAnnotations;
+		}, isPriority);
+	}
 }
 
 Zotero.PDFWorker = new PDFWorker();