diff --git a/web/src/compose.ts b/web/src/compose.ts
index c473e406b4..ed8db6f0b4 100644
--- a/web/src/compose.ts
+++ b/web/src/compose.ts
@@ -98,8 +98,7 @@ export function show_preview_area(): void {
 
 export function render_preview_area(): void {
     const $compose_textarea = $<HTMLTextAreaElement>("textarea#compose-textarea");
-    const content = $compose_textarea.val();
-    assert(content !== undefined);
+    const content = compose_state.message_content();
     const $preview_message_area = $("#compose .preview_message_area");
     compose_ui.render_and_show_preview(
         $("#compose"),