diff --git a/src/calibre/utils/fonts/scanner.py b/src/calibre/utils/fonts/scanner.py
index c1985250e2..d435e07a6e 100644
--- a/src/calibre/utils/fonts/scanner.py
+++ b/src/calibre/utils/fonts/scanner.py
@@ -200,7 +200,7 @@ class FontScanner(Thread):
     CACHE_VERSION = 2
 
     def __init__(self, folders=[], allowed_extensions={'ttf', 'otf'}):
-        Thread.__init__(self)
+        super().__init__(daemon=True)
         self.folders = folders + font_dirs() + [os.path.join(config_dir, 'fonts'),
                 P('fonts/liberation')]
         self.folders = [os.path.normcase(os.path.abspath(f)) for f in