diff --git a/internal/arrs/registrar/manager.go b/internal/arrs/registrar/manager.go
index 5f0a37e4e..fcd13adc6 100644
--- a/internal/arrs/registrar/manager.go
+++ b/internal/arrs/registrar/manager.go
@@ -14,6 +14,12 @@ import (
 	"golift.io/starr/sonarr"
 )
 
+// AltmountDownloadClientName is the name AltMount registers itself under as a
+// SABnzbd-compatible download client in Radarr/Sonarr/Lidarr/etc. Other code
+// (e.g. the queue cleanup worker) imports this to distinguish AltMount's own
+// queue items from those owned by other download clients.
+const AltmountDownloadClientName = "AltMount (SABnzbd)"
+
 type Manager struct {
 	instances *instances.Manager
 	clients   *clients.Manager
@@ -366,7 +372,7 @@ func (m *Manager) EnsureWebhookRegistration(ctx context.Context, altmountURL str
 // EnsureDownloadClientRegistration ensures that AltMount is registered as a SABnzbd download client in all enabled ARR instances
 func (m *Manager) EnsureDownloadClientRegistration(ctx context.Context, altmountHost string, altmountPort int, urlBase string, apiKey string) error {
 	allInstances := m.instances.GetAllInstances()
-	clientName := "AltMount (SABnzbd)"
+	clientName := AltmountDownloadClientName
 
 	slog.InfoContext(ctx, "Ensuring AltMount download client registration in ARR instances",
 		"host", altmountHost,
diff --git a/internal/arrs/worker/worker.go b/internal/arrs/worker/worker.go
index 2778a8552..e16caa865 100644
--- a/internal/arrs/worker/worker.go
+++ b/internal/arrs/worker/worker.go
@@ -13,6 +13,7 @@ import (
 	"github.com/javi11/altmount/internal/arrs/clients"
 	"github.com/javi11/altmount/internal/arrs/instances"
 	"github.com/javi11/altmount/internal/arrs/model"
+	"github.com/javi11/altmount/internal/arrs/registrar"
 	"github.com/javi11/altmount/internal/config"
 	"github.com/javi11/altmount/internal/database"
 	"golift.io/starr"
@@ -179,6 +180,13 @@ func (w *Worker) cleanupRadarrQueue(ctx context.Context, instance *model.ConfigI
 
 	var idsToRemove []int64
 	for _, q := range queue.Records {
+		// Only operate on queue items owned by AltMount's registered download client.
+		// Items from other clients (qBittorrent, real SABnzbd, etc.) may reference
+		// paths AltMount cannot see and must never be touched — see issue #523.
+		if q.DownloadClient != registrar.AltmountDownloadClientName {
+			continue
+		}
+
 		// Strategy 1: Ghost detection — cleanup already-imported files
 		if w.checkGhostByImportHistory(ctx, q.OutputPath, cfg, instance.Name, q.Title) {
 			idsToRemove = append(idsToRemove, q.ID)
@@ -301,6 +309,13 @@ func (w *Worker) cleanupSonarrQueue(ctx context.Context, instance *model.ConfigI
 
 	var idsToRemove []int64
 	for _, q := range queue.Records {
+		// Only operate on queue items owned by AltMount's registered download client.
+		// Items from other clients (qBittorrent, real SABnzbd, etc.) may reference
+		// paths AltMount cannot see and must never be touched — see issue #523.
+		if q.DownloadClient != registrar.AltmountDownloadClientName {
+			continue
+		}
+
 		// Strategy 1: Immediate cleanup for already imported files
 		if w.checkGhostByImportHistory(ctx, q.OutputPath, cfg, instance.Name, q.Title) {
 			idsToRemove = append(idsToRemove, q.ID)