diff --git a/src/backend/postgres/query.rs b/src/backend/postgres/query.rs
index cd2bc926..f0650110 100644
--- a/src/backend/postgres/query.rs
+++ b/src/backend/postgres/query.rs
@@ -41,9 +41,7 @@ impl QueryBuilder for PostgresQueryBuilder {
     fn prepare_simple_expr(&self, simple_expr: &SimpleExpr, sql: &mut dyn SqlWriter) {
         match simple_expr {
             SimpleExpr::AsEnum(type_name, expr) => {
-                let simple_expr = expr
-                    .clone()
-                    .cast_as_quoted(SeaRc::clone(type_name), self.quote());
+                let simple_expr = expr.clone().cast_as(SeaRc::clone(type_name));
                 self.prepare_simple_expr_common(&simple_expr, sql);
             }
             _ => QueryBuilder::prepare_simple_expr_common(self, simple_expr, sql),
diff --git a/src/expr.rs b/src/expr.rs
index 32a869c0..42a53254 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -3147,7 +3147,7 @@ impl Expr {
     /// );
     /// assert_eq!(
     ///     query.to_string(PostgresQueryBuilder),
-    ///     r#"SELECT CAST("font_size" AS "text") FROM "character""#
+    ///     r#"SELECT CAST("font_size" AS text) FROM "character""#
     /// );
     /// assert_eq!(
     ///     query.to_string(SqliteQueryBuilder),
@@ -3166,7 +3166,7 @@ impl Expr {
     /// );
     /// assert_eq!(
     ///     query.to_string(PostgresQueryBuilder),
-    ///     r#"INSERT INTO "character" ("font_size") VALUES (CAST('large' AS "FontSizeEnum"))"#
+    ///     r#"INSERT INTO "character" ("font_size") VALUES (CAST('large' AS FontSizeEnum))"#
     /// );
     /// assert_eq!(
     ///     query.to_string(SqliteQueryBuilder),