diff --git a/src/middleware.ts b/src/middleware.ts
index d454028..5eb6c39 100644
--- a/src/middleware.ts
+++ b/src/middleware.ts
@@ -3,7 +3,7 @@ import * as jose from "jose";
 import type { Middleware, Request } from "retes";
 import { Response } from "retes/response";
 
-import { SALEOR_AUTHORIZATION_BEARER_HEADER } from "./const";
+import { SALEOR_AUTHORIZATION_BEARER_HEADER, SALEOR_SIGNATURE_HEADER } from "./const";
 import { getSaleorHeaders } from "./headers";
 import { jwksUrl } from "./urls";
 
@@ -72,6 +72,13 @@ export const withWebhookSignatureVerified =
 
     const { domain: saleorDomain, signature: payloadSignature } = getSaleorHeaders(request.headers);
 
+    if (!payloadSignature) {
+      return Response.BadRequest({
+        success: false,
+        message: `${ERROR_MESSAGE} Missing ${SALEOR_SIGNATURE_HEADER} header.`,
+      });
+    }
+
     if (secretKey !== undefined) {
       const calculatedSignature = crypto
         .createHmac("sha256", secretKey)