diff --git a/types/random-js/index.d.ts b/types/random-js/index.d.ts
index ff1417b681..86926b9beb 100644
--- a/types/random-js/index.d.ts
+++ b/types/random-js/index.d.ts
@@ -27,7 +27,7 @@ interface Random {
     sample<T>(population: T[], sampleSize: number): T[];
     die(sideCount: number): number;
     dice(sideCount: number, dieCount: number): number[];
-    uuid4(engine: Random.Engine): string;
+    uuid4(engine?: Random.Engine): string;
     string(engine: Random.Engine, length: number): string;
     string(length?: number, pool?: string): string;
     hex(length?: number, upperCase?: boolean): string;
diff --git a/types/random-js/random-js-tests.ts b/types/random-js/random-js-tests.ts
index ef438e18c5..936a2a4693 100644
--- a/types/random-js/random-js-tests.ts
+++ b/types/random-js/random-js-tests.ts
@@ -86,7 +86,8 @@ sampled = random.sample(customTypeArray, 2);
 numeric = random.die(5);
 dieValues = random.dice(5, 2);
 
-uuid = Random.uuid4(engine);
+uuid = random.uuid4(engine);
+uuid = random.uuid4();
 
 str = random.string();
 str = random.string(10);