diff --git a/typings/index.d.ts b/typings/index.d.ts
index 43c536187..c0188727d 100644
--- a/typings/index.d.ts
+++ b/typings/index.d.ts
@@ -299,7 +299,7 @@ export interface RenderOptions {
 }
 
 type Debug = {
-  (message?: string);
+  (message?: string): void;
   shallow: (message?: string) => void;
 };