diff --git a/youtube_dl/jsinterp.py b/youtube_dl/jsinterp.py
index 4a5a0dbc3..a7440c582 100644
--- a/youtube_dl/jsinterp.py
+++ b/youtube_dl/jsinterp.py
@@ -131,8 +131,9 @@ class JSInterpreter(object):
             if variable in local_vars:
                 obj = local_vars[variable]
             else:
-                obj = self._objects.setdefault(
-                    variable, self.extract_object(variable))
+                if variable not in self._objects:
+                    self._objects[variable] = self.extract_object(variable)
+                obj = self._objects[variable]
 
             if arg_str is None:
                 # Member access
@@ -203,7 +204,8 @@ class JSInterpreter(object):
             argvals = tuple([
                 int(v) if v.isdigit() else local_vars[v]
                 for v in m.group('args').split(',')])
-            self._functions.setdefault(fname, self.extract_function(fname))
+            if fname not in self._functions:
+                self._functions[fname] = self.extract_function(fname)
             return self._functions[fname](argvals)
 
         raise ExtractorError('Unsupported JS expression %r' % expr)