diff --git a/src/tson.ts b/src/tson.ts
index 9a5d92cb..e792f4ed 100644
--- a/src/tson.ts
+++ b/src/tson.ts
@@ -77,22 +77,17 @@ export function tsonStringifier(opts: TsonOptions): TsonStringifyFn {
 
 export function tsonSerializer(opts: TsonOptions): TsonSerializeFn {
 	const handlers = (() => {
-		// warmup the type handlers
 		const types = opts.types.map((handler) => {
-			const key = handler.key as TsonTypeHandlerKey | undefined;
-			const serialize = handler.serialize;
-
 			type Serializer = (
 				value: unknown,
 				nonce: TsonNonce,
 				walk: WalkFn,
 			) => TsonSerializedValue;
 
-			const $serialize: Serializer = serialize
+			const $serialize: Serializer = handler.serialize
 				? (value, nonce, walk): TsonTuple => [
-						// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-						key!,
-						walk(serialize(value)),
+						handler.key as TsonTypeHandlerKey,
+						walk(handler.serialize(value)),
 						nonce,
 				  ]
 				: (value, _nonce, walk) => walk(value);
diff --git a/src/types.ts b/src/types.ts
index e9b1049d..a03940f9 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -36,11 +36,6 @@ export interface TsonTransformerNone {
 	 */
 	key?: never;
 	serialize?: never;
-
-	/**
-	 * Won't be deserialized nor serialized
-	 */
-	transform: false;
 }
 export interface TsonTransformerSerializeDeserialize<
 	TValue,
@@ -59,10 +54,6 @@ export interface TsonTransformerSerializeDeserialize<
 	 * JSON-serializable value
 	 */
 	serialize: (v: TValue) => TSerializedType;
-	/**
-	 * Use a transformer to serialize and deserialize the value?
-	 */
-	transform?: true;
 }
 
 export type TsonTransformer<TValue, TSerializedType extends SerializedType> =