diff --git a/src/editor/deserialize.js b/src/editor/deserialize.js
index 08827ca89a..d5efef5d1a 100644
--- a/src/editor/deserialize.js
+++ b/src/editor/deserialize.js
@@ -236,7 +236,7 @@ function parsePlainTextMessage(body, partCreator, isQuotedMessage) {
     return parts;
 }
 
-export function parseEvent(event, partCreator, {isQuotedMessage = false}) {
+export function parseEvent(event, partCreator, {isQuotedMessage = false} = {}) {
     const content = event.getContent();
     let parts;
     if (content.format === "org.matrix.custom.html") {
diff --git a/src/editor/serialize.js b/src/editor/serialize.js
index cb06eede6c..0746f6788e 100644
--- a/src/editor/serialize.js
+++ b/src/editor/serialize.js
@@ -33,7 +33,7 @@ export function mdSerialize(model) {
     }, "");
 }
 
-export function htmlSerializeIfNeeded(model, {forceHTML = false}) {
+export function htmlSerializeIfNeeded(model, {forceHTML = false} = {}) {
     const md = mdSerialize(model);
     const parser = new Markdown(md);
     if (!parser.isPlainText() || forceHTML) {