diff --git a/crates/oxc_ast/src/serialize/ts.rs b/crates/oxc_ast/src/serialize/ts.rs
index ceaa91c6375ba..c0e9328436836 100644
--- a/crates/oxc_ast/src/serialize/ts.rs
+++ b/crates/oxc_ast/src/serialize/ts.rs
@@ -209,7 +209,7 @@ impl ESTree for TSModuleDeclarationGlobal<'_, '_> {
 #[estree(
     ts_type = "TSMappedTypeModifierOperator | false",
     raw_deser = "
-        let optional = DESER[Option<TSMappedTypeModifierOperator>](POS_OFFSET.optional) || false;
+        let optional = DESER[Option<TSMappedTypeModifierOperator>](POS_OFFSET.optional);
         if (optional === null) optional = false;
         optional
     "
diff --git a/napi/parser/generated/deserialize/js.js b/napi/parser/generated/deserialize/js.js
index 6eb0537d49671..cd0df7a2ae09a 100644
--- a/napi/parser/generated/deserialize/js.js
+++ b/napi/parser/generated/deserialize/js.js
@@ -1916,7 +1916,7 @@ function deserializeTSConstructorType(pos) {
 }
 
 function deserializeTSMappedType(pos) {
-  let optional = deserializeOptionTSMappedTypeModifierOperator(pos + 48) || false;
+  let optional = deserializeOptionTSMappedTypeModifierOperator(pos + 48);
   if (optional === null) optional = false;
   const typeParameter = deserializeBoxTSTypeParameter(pos + 8);
   return {
diff --git a/napi/parser/generated/deserialize/ts.js b/napi/parser/generated/deserialize/ts.js
index efd33ffcb1972..f57ebc3993f1e 100644
--- a/napi/parser/generated/deserialize/ts.js
+++ b/napi/parser/generated/deserialize/ts.js
@@ -2068,7 +2068,7 @@ function deserializeTSConstructorType(pos) {
 }
 
 function deserializeTSMappedType(pos) {
-  let optional = deserializeOptionTSMappedTypeModifierOperator(pos + 48) || false;
+  let optional = deserializeOptionTSMappedTypeModifierOperator(pos + 48);
   if (optional === null) optional = false;
   const typeParameter = deserializeBoxTSTypeParameter(pos + 8);
   return {