diff --git a/youtube_dl/jsinterp.py b/youtube_dl/jsinterp.py
index 449482d3c..d7e76713f 100644
--- a/youtube_dl/jsinterp.py
+++ b/youtube_dl/jsinterp.py
@@ -59,7 +59,7 @@ def interpret_expression(self, expr, local_vars, allow_recursion):
             if member == 'split("")':
                 return list(val)
             if member == 'join("")':
-                return u''.join(val)
+                return ''.join(val)
             if member == 'length':
                 return len(val)
             if member == 'reverse()':