diff --git a/frontend/src/lib/document/viewer/PdfViewer.svelte b/frontend/src/lib/document/viewer/PdfViewer.svelte
index d79d16fc..311033c8 100644
--- a/frontend/src/lib/document/viewer/PdfViewer.svelte
+++ b/frontend/src/lib/document/viewer/PdfViewer.svelte
@@ -39,6 +39,7 @@ let {
 	libLoader?: LibLoader;
 } = $props();
 
+// untrack: libLoader prop change must not reinitialise the renderer
 const renderer = untrack(() => createPdfRenderer(libLoader));
 
 // Canvas and text layer container refs — bound via bind:this