diff --git a/luigi/contrib/hadoop.py b/luigi/contrib/hadoop.py
index 595e7bedec..959a759cee 100644
--- a/luigi/contrib/hadoop.py
+++ b/luigi/contrib/hadoop.py
@@ -971,7 +971,7 @@ def dump(self, directory=''):
             if self.__module__ == '__main__':
                 d = pickle.dumps(self)
                 module_name = os.path.basename(sys.argv[0]).rsplit('.', 1)[0]
-                d = d.replace(b'(c__main__', "(c" + module_name)
+                d = d.replace(b'(c__main__', b'(c' + module_name.encode('utf8'))
                 open(file_name, "wb").write(d)
 
             else: