diff --git a/internal/docduty/revoke.go b/internal/docduty/revoke.go
index 641cf084..07017df6 100644
--- a/internal/docduty/revoke.go
+++ b/internal/docduty/revoke.go
@@ -153,13 +153,13 @@ func clearDutySlotSQL(duty string) (string, bool) {
 		return `
 			UPDATE document_records
 			SET reviewer_id = NULL, reviewer_name = '', updated_at = now()
-			WHERE project_id = $1 AND COALESCE(task_key, '') <> '' AND reviewer_id = $2
+			WHERE project_id = $1 AND COALESCE(task_key, '') <> '' AND reviewer_id = $2 AND NOT duty_locked
 		`, true
 	case DutyApprover:
 		return `
 			UPDATE document_records
 			SET approver_id = NULL, approver_name = '', updated_at = now()
-			WHERE project_id = $1 AND COALESCE(task_key, '') <> '' AND approver_id = $2
+			WHERE project_id = $1 AND COALESCE(task_key, '') <> '' AND approver_id = $2 AND NOT duty_locked
 		`, true
 	default:
 		return "", false
diff --git a/internal/docduty/store.go b/internal/docduty/store.go
index ec45112d..da12502f 100644
--- a/internal/docduty/store.go
+++ b/internal/docduty/store.go
@@ -108,7 +108,7 @@ func backfillMissingDocumentDuties(ctx context.Context, db dutyDB, projectID int
 		       COALESCE(reviewer_id, 0), COALESCE(reviewer_name, ''),
 		       COALESCE(approver_id, 0), COALESCE(approver_name, '')
 		FROM document_records
-		WHERE project_id = $1 AND COALESCE(task_key, '') <> ''
+		WHERE project_id = $1 AND COALESCE(task_key, '') <> '' AND NOT duty_locked
 	`, projectID)
 	if err != nil {
 		return 0, fmt.Errorf("docduty: list documents: %w", err)