diff --git a/src/factories/transform.ts b/src/factories/transform.ts
index 5096f30..bf227f8 100644
--- a/src/factories/transform.ts
+++ b/src/factories/transform.ts
@@ -140,7 +140,8 @@ export const either =
  *     };
  *
  * @typeParam T - The validated type
- * @param first  - The validator
+ * @param first - The validator
  */
-export const optional = <T>(validator: Validator<T>): Validator<T | undefined> =>
-  either(validator, isUndefined);
+export const optional = <T>(
+  validator: Validator<T>,
+): Validator<T | undefined> => either(validator, isUndefined);
diff --git a/src/factories/validate.spec.ts b/src/factories/validate.spec.ts
index c66591c..13f04db 100644
--- a/src/factories/validate.spec.ts
+++ b/src/factories/validate.spec.ts
@@ -75,7 +75,10 @@ describe("validateWith", () => {
     expect(validator({ a: "1" }).parsed).toEqual({ a: "1", b: undefined });
 
     expect(validator({ a: "1", b: undefined }).valid).toBe(true);
-    expect(validator({ a: "1", b: undefined }).parsed).toEqual({ a: "1", b: undefined });
+    expect(validator({ a: "1", b: undefined }).parsed).toEqual({
+      a: "1",
+      b: undefined,
+    });
 
     expect(validator({ a: "1", b: 1 }).error).toEqual({ b: "Not a string: 1" });
     expect(validator({ a: "1", b: "1" }).parsed).toEqual({ a: "1", b: 1 });
@@ -144,7 +147,10 @@ describe("validateWithAtLeast", () => {
     expect(validator({ a: "1" }).parsed).toEqual({ a: "1", b: undefined });
 
     expect(validator({ a: "1", b: undefined }).valid).toBe(true);
-    expect(validator({ a: "1", b: undefined }).parsed).toEqual({ a: "1", b: undefined });
+    expect(validator({ a: "1", b: undefined }).parsed).toEqual({
+      a: "1",
+      b: undefined,
+    });
 
     expect(validator({ a: "1", b: 1 }).error).toEqual({ b: "Not a string: 1" });
     expect(validator({ a: "1", b: "1" }).parsed).toEqual({ a: "1", b: 1 });