diff --git a/package.json b/package.json
index ef6980b..1c3f135 100644
--- a/package.json
+++ b/package.json
@@ -59,7 +59,7 @@
 		"lodash.isequal": "^4.5.0",
 		"nyc": "^11.2.1",
 		"tslint": "^5.8.0",
-		"tslint-xo": "^0.3.0",
+		"tslint-xo": "^0.4.0",
 		"typedoc": "^0.9.0",
 		"typescript": "^2.6.2",
 		"vali-date": "^1.0.0",
diff --git a/source/lib/operators/not.ts b/source/lib/operators/not.ts
index ffcc143..0d38ace 100644
--- a/source/lib/operators/not.ts
+++ b/source/lib/operators/not.ts
@@ -1,4 +1,4 @@
-import {Predicate, Validator, validatorSymbol} from '../predicates/predicate';
+import {Predicate, validatorSymbol} from '../predicates/predicate';
 
 /**
  * Operator which inverts all the validations.
@@ -7,7 +7,7 @@ import {Predicate, Validator, validatorSymbol} from '../predicates/predicate';
  * @param predictate Predicate to wrap inside the operator.
  */
 export const not = <T extends Predicate>(predicate: T) => {
-	predicate.addValidator = (validator: Validator<any>) => {
+	predicate.addValidator = validator => {
 		const fn = validator.validator;
 		const message = validator.message;