diff --git a/README.md b/README.md
index 9fd55b4..9ab133a 100644
--- a/README.md
+++ b/README.md
@@ -94,7 +94,7 @@ import { getObservableLifecycle } from 'ngx-observable-lifecycle';
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class ChildComponent {
-  @Input() input: number;
+  @Input() input: number | undefined | null;
 
   constructor() {
     const {
diff --git a/package.json b/package.json
index 746a768..31d2d82 100644
--- a/package.json
+++ b/package.json
@@ -77,7 +77,6 @@
     "protractor": "~7.0.0",
     "semantic-release": "^17.2.3",
     "ts-node": "~8.3.0",
-    "tsdef": "0.0.14",
     "typescript": "~4.4.4"
   },
   "repository": {
diff --git a/src/app/child/child.component.ts b/src/app/child/child.component.ts
index 15fd2b9..49a1934 100644
--- a/src/app/child/child.component.ts
+++ b/src/app/child/child.component.ts
@@ -7,7 +7,7 @@ import { getObservableLifecycle } from 'ngx-observable-lifecycle';
   changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class ChildComponent {
-  @Input() input: number;
+  @Input() input: number | undefined | null;
 
   constructor() {
     const {
diff --git a/yarn.lock b/yarn.lock
index 7500ed3..73bf0e6 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -12006,11 +12006,6 @@ ts-node@~8.3.0:
     source-map-support "^0.5.6"
     yn "^3.0.0"
 
-tsdef@0.0.14:
-  version "0.0.14"
-  resolved "https://registry.yarnpkg.com/tsdef/-/tsdef-0.0.14.tgz#fb401d58d5c08699091942981ac1b5fa8ef23412"
-  integrity sha512-UjMD4XKRWWFlFBfwKVQmGFT5YzW/ZaF8x6KpCDf92u9wgKeha/go3FU0e5WqDjXsCOdfiavCkfwfVHNDxRDGMA==
-
 tslib@2.3.1, tslib@^2.3.0, tslib@^2.3.1:
   version "2.3.1"
   resolved "https://registry.yarnpkg.com/tslib/-/tslib-2.3.1.tgz#e8a335add5ceae51aa261d32a490158ef042ef01"