diff --git a/extensions/matrix/src/channel.ts b/extensions/matrix/src/channel.ts
index 0522590356a..a6a33a7f627 100644
--- a/extensions/matrix/src/channel.ts
+++ b/extensions/matrix/src/channel.ts
@@ -379,7 +379,7 @@ export const matrixPlugin: ChannelPlugin<ResolvedMatrixAccount> = {
   },
   outbound: {
     deliveryMode: "direct",
-    chunker: (text, limit) => getMatrixRuntime().channel.text.chunkMarkdownText(text, limit),
+    chunker: (text, limit) => getMatrixRuntime().channel.text.chunkMarkdownText!(text, limit),
     chunkerMode: "markdown",
     textChunkLimit: 4000,
     sendText: async (params) => (await loadMatrixChannelRuntime()).matrixOutbound.sendText!(params),