diff --git a/sqlglot/dialects/dialect.py b/sqlglot/dialects/dialect.py
index fe93f62aea..532ab854c5 100644
--- a/sqlglot/dialects/dialect.py
+++ b/sqlglot/dialects/dialect.py
@@ -1584,9 +1584,9 @@ def normalize(identifier: t.Optional[exp.Identifier]) -> t.Optional[str]:
                     ):
                         equal_lhs.replace(exp.column(equal_lhs.this))
             if isinstance(then, exp.Insert):
-                column_list = then.args.get("this")
-                if column_list is not None:
-                    for column in column_list.find_all(exp.Column):
+                column_list = then.this
+                if isinstance(column_list, exp.Tuple):
+                    for column in column_list.expressions:
                         if normalize(column.args.get("table")) in targets:
                             column.replace(exp.column(column.this))