diff --git a/celery/app/log.py b/celery/app/log.py
index d27a85ee559..7e036746cc0 100644
--- a/celery/app/log.py
+++ b/celery/app/log.py
@@ -226,7 +226,7 @@ def _detect_handler(self, logfile=None):
         logfile = sys.__stderr__ if logfile is None else logfile
         if hasattr(logfile, 'write'):
             return logging.StreamHandler(logfile)
-        return WatchedFileHandler(logfile)
+        return WatchedFileHandler(logfile, encoding='utf-8')
 
     def _has_handler(self, logger):
         return any(