diff --git a/chrome/content/zotero/xpcom/data/item.js b/chrome/content/zotero/xpcom/data/item.js
index 37fadfde7f..20b5dd18b2 100644
--- a/chrome/content/zotero/xpcom/data/item.js
+++ b/chrome/content/zotero/xpcom/data/item.js
@@ -4237,7 +4237,12 @@ Zotero.Item.prototype.toJSON = function (options = {}) {
 		obj.dateModified = Zotero.Date.sqlToISO8601(this.dateModified);
 	}
 	
-	return this._postToJSON(env);
+	var json = this._postToJSON(env);
+	if (options.skipStorageProperties) {
+		delete json.md5;
+		delete json.mtime;
+	}
+	return json;
 }
 
 
diff --git a/test/tests/itemTest.js b/test/tests/itemTest.js
index 580b9e672d..c6cbf5ac30 100644
--- a/test/tests/itemTest.js
+++ b/test/tests/itemTest.js
@@ -1192,6 +1192,28 @@ describe("Zotero.Item", function () {
 				var json = note.toJSON({ patchBase });
 				assert.isFalse(json.parentItem);
 			});
+			
+			it("shouldn't clear storage properties from original in .skipStorageProperties mode", function* () {
+				var item = new Zotero.Item('attachment');
+				item.attachmentLinkMode = 'imported_file';
+				item.attachmentFilename = 'test.txt';
+				item.attachmentContentType = 'text/plain';
+				item.attachmentCharset = 'utf-8';
+				item.attachmentSyncedModificationTime = 1234567890000;
+				item.attachmentSyncedHash = '18d21750c8abd5e3afa8ea89e3dfa570';
+				var patchBase = item.toJSON({
+					syncedStorageProperties: true
+				});
+				item.setNote("Test");
+				var json = item.toJSON({
+					patchBase,
+					skipStorageProperties: true
+				});
+				Zotero.debug(json);
+				assert.equal(json.note, "Test");
+				assert.notProperty(json, "md5");
+				assert.notProperty(json, "mtime");
+			});
 		})
 	})