diff --git a/BookPlayer/AppDelegate.swift b/BookPlayer/AppDelegate.swift
index 770d6d25b..3428fa247 100644
--- a/BookPlayer/AppDelegate.swift
+++ b/BookPlayer/AppDelegate.swift
@@ -351,9 +351,8 @@ class AppDelegate: UIResponder, UIApplicationDelegate, BPLogger {
       // the raw query back under `http.query`, on both network breadcrumbs and `http.client` spans.
       // Only the userinfo portion is redacted for us. That leaks real secrets from hosts we don't
       // control: AudiobookShelf's OIDC exchange has to carry `code` and `code_verifier` in the query
-      // (its endpoint is GET-only), and Jellyfin's download URLs still carry `api_key`. Either one
-      // would be uploaded verbatim alongside the user's self-hosted hostname on the next captured
-      // event.
+      // (its endpoint is GET-only). Both would be uploaded verbatim alongside the user's self-hosted
+      // hostname on the next captured event.
       //
       // Our own backend authenticates with a bearer header and puts nothing sensitive in a query, so
       // its query strings are kept — that's where this data actually helps debugging.
diff --git a/BookPlayer/Jellyfin/Network/JellyfinConnectionService.swift b/BookPlayer/Jellyfin/Network/JellyfinConnectionService.swift
index f99a54aaf..032182834 100644
--- a/BookPlayer/Jellyfin/Network/JellyfinConnectionService.swift
+++ b/BookPlayer/Jellyfin/Network/JellyfinConnectionService.swift
@@ -723,17 +723,12 @@ class JellyfinConnectionService: BPLogger {
     return client
   }
 
-  func createItemDownloadUrl(_ item: JellyfinLibraryItem) throws -> URL {
-    guard let client else {
-      throw IntegrationError.noClient("Jellyfin")
-    }
-
+  /// Kept private because the returned URL is *not* self-authenticating — handing it
+  /// straight to `URLSession`/`AVURLAsset` would 401. Go through
+  /// `createItemDownloadRequest(_:)`, which attaches the token.
+  private func createItemDownloadUrl(_ item: JellyfinLibraryItem) throws -> URL {
     let request = Paths.getDownload(itemID: item.id)
-    var components = try createUrlComponentsForApiRequest(request)
-
-    var queryItems = components.queryItems ?? []
-    queryItems.append(URLQueryItem(name: "api_key", value: client.accessToken))
-    components.queryItems = queryItems
+    let components = try createUrlComponentsForApiRequest(request)
 
     guard let url = components.url else {
       throw IntegrationError.urlFromComponents(components)
@@ -742,11 +737,19 @@ class JellyfinConnectionService: BPLogger {
     return url
   }
 
-  /// Returns a URLRequest for downloading a library item, carrying the user-defined
-  /// custom HTTP headers (needed for servers behind Cloudflare Access etc.).
+  /// Returns a URLRequest for downloading a library item, carrying the access token plus the
+  /// user-defined custom HTTP headers (needed for servers behind Cloudflare Access etc.).
+  ///
+  /// The token goes in the `Authorization` header, not in an `?api_key=` query item: Jellyfin 12
+  /// servers can reject the query token with a 401, and a token in the URL leaks into the download task's
+  /// persisted `taskDescription`. It is set after the custom headers, so they can't clobber it.
   func createItemDownloadRequest(_ item: JellyfinLibraryItem) throws -> URLRequest {
     let url = try createItemDownloadUrl(item)
-    return wrapWithCustomHeaders(url)
+    var request = wrapWithCustomHeaders(url)
+    if let accessToken = client?.accessToken {
+      request.setValue("MediaBrowser Token=\"\(accessToken)\"", forHTTPHeaderField: "Authorization")
+    }
+    return request
   }
 
   /// Wraps an arbitrary URL (e.g. a cover image) in a URLRequest carrying the current
diff --git a/BookPlayerTests/MediaServerIntegration/JellyfinQuickConnectTests.swift b/BookPlayerTests/MediaServerIntegration/JellyfinQuickConnectTests.swift
index c4f42df80..b41589fb0 100644
--- a/BookPlayerTests/MediaServerIntegration/JellyfinQuickConnectTests.swift
+++ b/BookPlayerTests/MediaServerIntegration/JellyfinQuickConnectTests.swift
@@ -169,3 +169,52 @@ final class JellyfinQuickConnectTests: XCTestCase {
     }
   }
 }
+
+/// Covers the download request, which is built by hand instead of going through `JellyfinClient`
+/// and so gets none of the client's automatic auth. Jellyfin 12 servers can reject the `?api_key=` query
+/// token with a 401 and accept only the token in the `Authorization` header (#1598).
+@MainActor
+final class JellyfinDownloadRequestTests: XCTestCase {
+  private var sut: JellyfinConnectionService!
+
+  override func setUp() {
+    super.setUp()
+    sut = JellyfinConnectionService(keychainService: KeychainServiceMock())
+    sut.client = JellyfinClient(
+      configuration: JellyfinClient.Configuration(
+        url: URL(string: "https://jellyfin.example.com/jellyfin")!,
+        client: "BookPlayer",
+        deviceName: "Test Device",
+        deviceID: "test-device",
+        version: "1"
+      ),
+      accessToken: "s3cr3t"
+    )
+  }
+
+  override func tearDown() {
+    sut = nil
+    super.tearDown()
+  }
+
+  private let audiobook = JellyfinLibraryItem(id: "item-1", name: "Book", kind: .audiobook)
+
+  func testDownloadRequestCarriesTheTokenInTheAuthorizationHeader() throws {
+    let request = try sut.createItemDownloadRequest(audiobook)
+
+    XCTAssertEqual(
+      request.value(forHTTPHeaderField: "Authorization"),
+      "MediaBrowser Token=\"s3cr3t\""
+    )
+  }
+
+  /// The URL ends up in the download task's persisted `taskDescription`, so it must not carry the token.
+  func testDownloadURLDoesNotCarryTheToken() throws {
+    let request = try sut.createItemDownloadRequest(audiobook)
+    let url = try XCTUnwrap(request.url)
+
+    XCTAssertEqual(url.path, "/jellyfin/Items/item-1/Download")
+    XCTAssertFalse(url.absoluteString.contains("s3cr3t"))
+    XCTAssertFalse(url.absoluteString.contains("api_key"))
+  }
+}