diff --git a/chrome/content/zotero/xpcom/data/item.js b/chrome/content/zotero/xpcom/data/item.js
index 9cb769c2fe..0d29b2959e 100644
--- a/chrome/content/zotero/xpcom/data/item.js
+++ b/chrome/content/zotero/xpcom/data/item.js
@@ -3974,7 +3974,7 @@ Zotero.Item.prototype.hasEmbeddedAnnotations = async function () {
 	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 = /\s\/Subtype\s+\/(Text|FreeText|Line|Square|Circle|Polygon|PolyLine|Highlight|Underline|Squiggly|StrikeOut|Stamp|Caret|Ink|FileAttachment|Sound|Redact)\s/;
+	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);
 };
 
diff --git a/chrome/content/zotero/xpcom/data/items.js b/chrome/content/zotero/xpcom/data/items.js
index 3bb182f96b..8bb34febd8 100644
--- a/chrome/content/zotero/xpcom/data/items.js
+++ b/chrome/content/zotero/xpcom/data/items.js
@@ -956,11 +956,24 @@ Zotero.Items = function() {
 		if (fromItem.isFileAttachment()) {
 			let annotations = fromItem.getAnnotations(includeTrashed);
 			for (let annotation of annotations) {
+				if (annotation.annotationIsExternal) {
+					await annotation.erase();
+					continue;
+				}
 				annotation.parentItemID = toItem.id;
 				await annotation.save();
 			}
 		}
 		
+		if (toItem.isFileAttachment()) {
+			let annotations = toItem.getAnnotations(includeTrashed);
+			for (let annotation of annotations) {
+				if (annotation.annotationIsExternal) {
+					await annotation.erase();
+				}
+			}
+		}
+		
 		// TODO: Other things as necessary
 	};
 	
@@ -1129,16 +1142,15 @@ Zotero.Items = function() {
 				}
 
 				// Check whether master and other have embedded annotations
-				// Master yes, other yes -> keep both
-				// Master yes, other no -> keep master
-				// Master no, other yes -> keep other
 				if (await otherAttachment.hasEmbeddedAnnotations()) {
+					// Other yes, master yes -> keep both
 					if (await masterAttachment.hasEmbeddedAnnotations()) {
 						Zotero.debug(`Master attachment ${masterAttachment.key} matches ${otherAttachment.key}, `
 							+ 'but both have embedded annotations - keeping both');
 						otherAttachment.parentItemID = item.id;
 						await otherAttachment.save();
 					}
+					// Other yes, master no -> keep other
 					else {
 						Zotero.debug(`Master attachment ${masterAttachment.key} matches ${otherAttachment.key}, `
 							+ 'but other has embedded annotations - merging into other');
@@ -1148,6 +1160,8 @@ Zotero.Items = function() {
 					}
 					continue;
 				}
+				// Other no, master yes -> keep master
+				// Other no, master no -> keep master
 
 				Zotero.debug(`Master attachment ${masterAttachment.key} matches ${otherAttachment.key} - merging into master`);
 				await doMerge(otherAttachment, masterAttachment);