diff --git a/eldoc-box.el b/eldoc-box.el
index 2ca3275..9e47fac 100644
--- a/eldoc-box.el
+++ b/eldoc-box.el
@@ -287,6 +287,7 @@ STR has to be a proper documentation, not empty string, not nil, etc."
   (let ((doc-buffer (get-buffer-create eldoc-box--buffer)))
     (with-current-buffer doc-buffer
       (setq mode-line-format nil)
+      (setq header-line-format nil)
       ;; WORKAROUND: (issue#66) If cursor-type is ‘box’, sometimes the
       ;; cursor is still shown for some reason.
       (setq-local cursor-type t)