diff --git a/types/winston/index.d.ts b/types/winston/index.d.ts
index d28a83b574..a189f03c22 100644
--- a/types/winston/index.d.ts
+++ b/types/winston/index.d.ts
@@ -400,7 +400,7 @@ declare namespace winston {
         label?: string;
         depth?: number;
 
-        timestamp: boolean | (() => string | boolean);
+        timestamp?: boolean | (() => string | boolean);
         stringify?(obj: any): string;
     }