diff --git a/data/maker/prepare/__init__.py b/data/maker/prepare/__init__.py
index f7ae3f7..3ef494e 100644
--- a/data/maker/prepare/__init__.py
+++ b/data/maker/prepare/__init__.py
@@ -96,7 +96,7 @@ class Input :
             # self._columns  = cols if cols else _df.apply(lambda col:None if col[0] == row_count or col[0] < MIN_SPACE_SIZE else col.name).dropna().tolist()
             # self._io = _df.to_dict(orient='records')
             _df  = self.df.nunique().T / self.df.shape[0]
-            self._io = _df.to_dict(orient='records')
+            self._io = pd.DataFrame(_df).to_dict(orient='records')
         except Exception as e:
             print (e)
             self._io = []