diff --git a/src/calibre/gui2/viewer/web_view.py b/src/calibre/gui2/viewer/web_view.py
index ab02c8130b..ce33c5e554 100644
--- a/src/calibre/gui2/viewer/web_view.py
+++ b/src/calibre/gui2/viewer/web_view.py
@@ -282,6 +282,7 @@ class WebPage(QWebEnginePage):
             return True
         if url.scheme() in ('http', 'https'):
             safe_open_url(url)
+        prints('Blocking navigation request to:', url.toString())
         return False
 
     def go_to_anchor(self, anchor):