diff --git a/sinon/index.d.ts b/sinon/index.d.ts
index be0d3820bb..7c44ab9d7a 100644
--- a/sinon/index.d.ts
+++ b/sinon/index.d.ts
@@ -109,7 +109,7 @@ declare namespace Sinon {
         callsArgOnAsync(index: number, context: any): SinonStub;
         callsArgWithAsync(index: number, ...args: any[]): SinonStub;
         callsArgOnWithAsync(index: number, context: any, ...args: any[]): SinonStub;
-        callsFake(...args: any[]): SinonStub;
+        callsFake(func: (...args: any[]) => void): SinonStub;
         onCall(n: number): SinonStub;
         onFirstCall(): SinonStub;
         onSecondCall(): SinonStub;