diff --git a/cypress/component/helpers/yjs.cy.js b/cypress/component/helpers/yjs.cy.js
index 6f4d261383f..7472e28adc8 100644
--- a/cypress/component/helpers/yjs.cy.js
+++ b/cypress/component/helpers/yjs.cy.js
@@ -70,7 +70,7 @@ describe('Yjs base64 wrapped with our helpers', function() {
 		const stateA = getDocumentState(source)
 		const update0A = getUpdateMessage(source, state0)
 		const updateAA = getUpdateMessage(source, stateA)
-		expect(update0A.length).to.be.eq(40)
+		expect(update0A.length).to.be.eq(29)
 		expect(updateAA).to.be.eq(undefined)
 	})
 
diff --git a/src/helpers/yjs.js b/src/helpers/yjs.js
index 6ed897eff76..f4fc64a17e5 100644
--- a/src/helpers/yjs.js
+++ b/src/helpers/yjs.js
@@ -51,7 +51,7 @@ export function applyDocumentState(ydoc, documentState, origin) {
  *
  * @param {Y.Doc} ydoc - encode state of this doc
  * @param {string} encodedBaseUpdate - base64 encoded doc update to build upon
- * @return {string|undefined}
+ * @return {Uint8Array|undefined}
  */
 export function getUpdateMessage(ydoc, encodedBaseUpdate) {
 	const baseUpdate = decodeArrayBuffer(encodedBaseUpdate)
@@ -65,8 +65,7 @@ export function getUpdateMessage(ydoc, encodedBaseUpdate) {
 	encoding.writeVarUint(encoder, messageSync)
 	const update = Y.encodeStateAsUpdate(ydoc, baseStateVector)
 	syncProtocol.writeUpdate(encoder, update)
-	const buf = encoding.toUint8Array(encoder)
-	return encodeArrayBuffer(buf)
+	return encoding.toUint8Array(encoder)
 }
 
 /**
@@ -74,12 +73,11 @@ export function getUpdateMessage(ydoc, encodedBaseUpdate) {
  *
  * Only used in tests right now.
  * @param {Y.Doc} ydoc - encode state of this doc
- * @param {string} updateMessage - base64 encoded y-websocket sync message with update
+ * @param {Uint8Array} updateMessage - y-websocket sync message with update
  * @param {object} origin - initiator object e.g. WebsocketProvider
  */
 export function applyUpdateMessage(ydoc, updateMessage, origin = 'origin') {
-	const updateBuffer = decodeArrayBuffer(updateMessage)
-	const decoder = decoding.createDecoder(updateBuffer)
+	const decoder = decoding.createDecoder(updateMessage)
 	const messageType = decoding.readVarUint(decoder)
 	if (messageType !== messageSync) {
 		console.error('y.js update message with invalid type', messageType)