diff --git a/youtube_dl/YoutubeDL.py b/youtube_dl/YoutubeDL.py
index 04771c6372..adeef23af0 100644
--- a/youtube_dl/YoutubeDL.py
+++ b/youtube_dl/YoutubeDL.py
@@ -688,7 +688,12 @@ def _free_formats_key(f):
                         ext_ord)
             formats = sorted(formats, key=_free_formats_key)
 
-        info_dict['formats'] = formats
+        if formats[0] is not info_dict: 
+            # only set the 'formats' fields if the original info_dict list them
+            # otherwise we end up with a circular reference, the first (and unique)
+            # element in the 'formats' field in info_dict is info_dict itself, 
+            # wich can't be exported to json
+            info_dict['formats'] = formats
         if self.params.get('listformats', None):
             self.list_formats(info_dict)
             return