diff --git a/plugins/file-manager/src/frontend/FileManagerSidebar.tsx b/plugins/file-manager/src/frontend/FileManagerSidebar.tsx
index 9ad117cb3..a51095ddc 100644
--- a/plugins/file-manager/src/frontend/FileManagerSidebar.tsx
+++ b/plugins/file-manager/src/frontend/FileManagerSidebar.tsx
@@ -27,7 +27,7 @@ import {
   removeFolderShortcut,
 } from "./api/file-manager-data-api";
 import { listSSHFiles } from "./api/ssh-file-operations-api";
-import type { DiskFilesystem } from "./disk-info";
+import { mountForPath, type DiskFilesystem } from "./disk-info";
 import { toast } from "sonner";
 import FolderTree from "./components/FolderTree";
 import {
@@ -702,11 +702,13 @@ export function FileManagerSidebar({
   // ─── Render ───────────────────────────────────────────────────────────────────
 
   const storageFilesystems = diskInfo?.filesystems ?? [];
-  const activeStorageMount = selectedMount ?? diskInfo?.mount ?? null;
+  const pathFs = mountForPath(storageFilesystems, currentPath);
+  const activeStorageMount =
+    selectedMount ?? pathFs?.mount ?? diskInfo?.mount ?? null;
   const selectedFs =
     selectedMount !== null
       ? (storageFilesystems.find((fs) => fs.mount === selectedMount) ?? null)
-      : null;
+      : pathFs;
 
   const storage =
     selectedFs && selectedFs.percent !== null
diff --git a/plugins/file-manager/src/frontend/disk-info.ts b/plugins/file-manager/src/frontend/disk-info.ts
index 238e82980..2347841ae 100644
--- a/plugins/file-manager/src/frontend/disk-info.ts
+++ b/plugins/file-manager/src/frontend/disk-info.ts
@@ -20,3 +20,19 @@ export interface HostDiskInfo {
   mount: string | null;
   filesystems?: DiskFilesystem[];
 }
+
+/** The filesystem the path lives on: the longest mount point that holds it. */
+export function mountForPath(
+  filesystems: DiskFilesystem[],
+  path: string | null | undefined,
+): DiskFilesystem | null {
+  if (!path) return null;
+  let best: DiskFilesystem | null = null;
+  for (const fs of filesystems) {
+    const mount = fs.mount.replace(/\/+$/, "") || "/";
+    const inside =
+      mount === "/" || path === mount || path.startsWith(`${mount}/`);
+    if (inside && (!best || mount.length > best.mount.length)) best = fs;
+  }
+  return best;
+}
diff --git a/plugins/file-manager/tests/frontend/disk-info.test.ts b/plugins/file-manager/tests/frontend/disk-info.test.ts
new file mode 100644
index 000000000..e4ea96ece
--- /dev/null
+++ b/plugins/file-manager/tests/frontend/disk-info.test.ts
@@ -0,0 +1,35 @@
+import { describe, expect, it } from "vitest";
+import {
+  mountForPath,
+  type DiskFilesystem,
+} from "../../src/frontend/disk-info";
+
+function fs(mount: string): DiskFilesystem {
+  return {
+    filesystem: mount,
+    type: "ext4",
+    mount,
+    percent: 10,
+    usedHuman: "1G",
+    totalHuman: "10G",
+    availableHuman: "9G",
+    usedBytes: 1,
+    totalBytes: 10,
+    availableBytes: 9,
+  };
+}
+
+describe("mountForPath", () => {
+  const list = [fs("/"), fs("/volume1"), fs("/volume10")];
+
+  it("picks the deepest mount that holds the path", () => {
+    expect(mountForPath(list, "/volume1/share")?.mount).toBe("/volume1");
+    expect(mountForPath(list, "/volume10")?.mount).toBe("/volume10");
+    expect(mountForPath(list, "/etc")?.mount).toBe("/");
+  });
+
+  it("returns null without a path or mounts", () => {
+    expect(mountForPath(list, null)).toBeNull();
+    expect(mountForPath([], "/etc")).toBeNull();
+  });
+});