diff --git a/wetb/prepost/misc.py b/wetb/prepost/misc.py
index b6129907304a3cb7c58fef4cf63f0368315312eb..caa424d00df9cd892e570c50ce0fbe72f3fd1c33 100644
--- a/wetb/prepost/misc.py
+++ b/wetb/prepost/misc.py
@@ -1113,8 +1113,10 @@ def df_dict_check_datatypes(df_dict):
     # we can not pop/delete items from a dict while iterating over it
     df_dict2 = {}
     for colkey, col in df_dict.items():
+        if len(col)==0:
+            pass
         # if we have a list, convert to string
-        if type(col[0]).__name__ == 'list':
+        elif type(col[0]).__name__ == 'list':
             for ii, item in enumerate(col):
                 col[ii] = '**'.join(item)
         # if we already have an array (statistics) or a list of numbers