diff --git a/lineagex/ColumnLineageNoConn.py b/lineagex/ColumnLineageNoConn.py
index 1a44182..e6758c7 100644
--- a/lineagex/ColumnLineageNoConn.py
+++ b/lineagex/ColumnLineageNoConn.py
@@ -247,7 +247,8 @@ def _handle_union(self, sql_ast: expressions = None) -> None:
                 cols = self._find_alias_col(
                     col_sql=col.sql(), temp_table=main_tables, ref=True
                 )
-                # print(col, cols[0], cols[1])
+                if col.dump()["args"]["this"]["args"]["quoted"] is True:
+                    continue
                 self.all_used_col.extend(cols[0] + cols[1])
             return
 
@@ -696,7 +697,7 @@ def _shared_col_conds(
                     temp_c = []
                     for k, v in dummy_dict.items():
                         temp_c.extend(list(itertools.chain.from_iterable(v)))
-                    self.all_used_col.extend(list(set(temp_c)))
+                    list(self.all_used_col).extend(list(set(temp_c)))
                     used_tables = self._find_all_tables(
                         temp_table_list=self._resolve_table(part_ast=temp_ast)
                     )
@@ -706,7 +707,7 @@ def _shared_col_conds(
                     cols = self._find_alias_col(
                         col_sql=cond_col.sql(), temp_table=used_tables, ref=True
                     )
-                    self.all_used_col.extend(cols[0] + cols[1])
+                    list(self.all_used_col).extend(cols[0] + cols[1])
 
     def _find_alias_col(
         self,
diff --git a/pyproject.toml b/pyproject.toml
index e4f7f08..0ae5660 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "lineagex"
-version = "0.0.20"
+version = "0.0.21"
 description = "A column lineage tool"
 authors = ["zshandy <zshandy@gmail.com>"]
 license = "MIT"