diff --git a/ui/src/components/BlobPreview.svelte b/ui/src/components/BlobPreview.svelte
index c82bf8b..d2f901a 100644
--- a/ui/src/components/BlobPreview.svelte
+++ b/ui/src/components/BlobPreview.svelte
@@ -4,9 +4,8 @@
 
   $: ({ attributes } = useEntity(address));
 
-  let mimeType: string | undefined;
-  $: mimeType = $attributes.find(([_, e]) => e.attribute === "FILE_MIME")?.[1]
-    .value.c;
+  $: mimeType = String($attributes.find(([_, e]) => e.attribute === "FILE_MIME")?.[1]
+    .value.c);
 </script>
 
 <div class="preview" v-if="mimeType">