diff --git a/Web/app.py b/Web/app.py
index f229043..a72e0e9 100755
--- a/Web/app.py
+++ b/Web/app.py
@@ -7047,6 +7047,7 @@ def ausleihen(id):
         if current_permissions['actions'].get('can_borrow') and not is_library_item:
             if student_card_id:
                 student_user = us.get_user_by_student_card(student_card_id)
+                app.logger.debug(f"Borrowing on behalf of student card {student_card_id}: found user {student_user}")
                 if not student_user:
                     flash('Keine Schülerin/kein Schüler mit dieser Ausweis-ID gefunden.', 'error')
                     return redirect(url_for('library'))