diff --git a/typescript/option/docs/main.md b/typescript/option/docs/main.md
index e2c05a2..db1f2ec 100644
--- a/typescript/option/docs/main.md
+++ b/typescript/option/docs/main.md
@@ -194,7 +194,7 @@ A function to create options from nullable values.
 ### Signature
 
 ```ts
-const fromNullable: <T>(value: T | null) => Option<T>
+const fromNullable: <T>(value: Nullable<T>) => Option<T>
 ```
 
 ### Usage
diff --git a/typescript/option/src/helpers.ts b/typescript/option/src/helpers.ts
index 09a419f..629e830 100644
--- a/typescript/option/src/helpers.ts
+++ b/typescript/option/src/helpers.ts
@@ -1,5 +1,12 @@
 import { Option, Some, None } from './types'
-import { Binder, Folder, Mapper, Predicate, BackFolder } from './internalTypes'
+import {
+    Binder,
+    Folder,
+    Mapper,
+    Predicate,
+    BackFolder,
+    Nullable
+} from './internalTypes'
 import { always, identity } from './internalHelperts'
 import Internals, { SomeClass, isOption } from './internals'
 
@@ -106,6 +113,6 @@ export const flat = <T, U>(option: Option<T>): Option<U> => {
     )
 }
 
-export const fromNullable = <T>(value: null | T): Option<T> => {
+export const fromNullable = <T>(value: Nullable<T>): Option<T> => {
     return value === null ? None : Some(value)
 }
diff --git a/typescript/option/src/internalTypes.ts b/typescript/option/src/internalTypes.ts
index a636b21..091ab91 100644
--- a/typescript/option/src/internalTypes.ts
+++ b/typescript/option/src/internalTypes.ts
@@ -5,3 +5,4 @@ export type Binder<T, U> = Mapper<T, Option<U>>
 export type Predicate<T> = Mapper<T, boolean>
 export type Folder<T, U> = (s: U, v: T) => U
 export type BackFolder<T, U> = (v: T, s: U) => U
+export type Nullable<T> = T | null