diff --git a/src/caosadvancedtools/table_converter.py b/src/caosadvancedtools/table_converter.py
index 54b25185db948bcd4a3a92b488919e4bfe7c4920..74bd857cdbc6f7e3473884fbf988017ef200ef88 100644
--- a/src/caosadvancedtools/table_converter.py
+++ b/src/caosadvancedtools/table_converter.py
@@ -59,10 +59,10 @@ def to_table(container):
         properties.update([generate_property_name(p)
                            for p in container[0].get_properties()])
     df = pd.DataFrame(columns=list(properties))
-    rts = set([p.name for p in container[0].parents])
+    rts = {p.name for p in container[0].parents}
 
     for ii, rec in enumerate(container):
-        if set([p.name for p in rec.parents]) != rts:
+        if {p.name for p in rec.parents} != rts:
             raise ValueError("Parents differ")
 
         for prop in rec.get_properties():
@@ -70,7 +70,7 @@ def to_table(container):
             if isinstance(prop.value, list):
                 if propname not in df:
                     df[propname] = pd.Series(dtype=object)
-                elif df[propname].dtype != np.dtypes.ObjectDType:
+                elif df[propname].dtype != object:
                     df[propname] = df[propname].astype(object)
             df.at[ii, propname] = prop.value