diff --git a/docker/frontend/src/Library.tsx b/docker/frontend/src/Library.tsx
index dcf9687..5607537 100644
--- a/docker/frontend/src/Library.tsx
+++ b/docker/frontend/src/Library.tsx
@@ -1586,7 +1586,6 @@ function Catalogue({ admin, user }: { admin: boolean; user: User | null }) {
       const normRoot = normPath(rootName);
       const normKey = normPath(key);
       if (normKey === normRoot) return '';
-      if (normRoot === '') return `${normKey}/`;
       if (normKey.startsWith(`${normRoot}/`)) return `${normKey.slice(normRoot.length + 1)}/`;
       return null;
     },
@@ -1766,7 +1765,7 @@ function Catalogue({ admin, user }: { admin: boolean; user: User | null }) {
       // indented rows have to come in.
       for (const dir of [...(foldersUnder.get(lowerF) ?? [])].sort((a, b) => a.localeCompare(b))) {
         const parts = dir.split('/');
-        const key = normF ? `${normF}/${dir}` : dir;
+        const key = `${normF}/${dir}`;
         out.push({
           key,
           label: parts[parts.length - 1],
diff --git a/docker/frontend/src/engine/library.ts b/docker/frontend/src/engine/library.ts
index 1808b2a..dd9da83 100644
--- a/docker/frontend/src/engine/library.ts
+++ b/docker/frontend/src/engine/library.ts
@@ -1390,7 +1390,11 @@ export async function scanFolder(
   // been read once before is a reading of a hundred thousand frames even while
   // the walk is still up in its first folders, and one kept to a subfolder is
   // measured against the frames under that one alone.
-  const heldPrefix = `${folder.name}/${from}`.toLowerCase();
+  // An id is `normPath(folder.name)/…`, and a drive root is named `\`, which
+  // `normPath` spells `''` — so the frames of such a roll's subfolder are filed
+  // under `/Roll/…`, and a prefix built as `${folder.name}/${from}` spells
+  // `\/Roll` and counts nought of them held.
+  const heldPrefix = `${normPath(folder.name)}/${normPath(from)}`.toLowerCase();
   const held = bounded
     ? rawKnown.filter((p) => p.id.toLowerCase().startsWith(heldPrefix)).length
     : rawKnown.length;