diff --git a/src/Signer/DefaultSigner.php b/src/Signer/DefaultSigner.php
index 11cc1a0..acf495b 100644
--- a/src/Signer/DefaultSigner.php
+++ b/src/Signer/DefaultSigner.php
@@ -4,7 +4,7 @@
 
 class DefaultSigner implements Signer
 {
-    public function calculateSignature(array $payload, string $secret): string
+    public function calculateSignature(string $webhookUrl, array $payload, string $secret): string
     {
         $payloadJson = json_encode($payload);
 
diff --git a/src/Signer/Signer.php b/src/Signer/Signer.php
index 5bfd95b..a5fc0ed 100644
--- a/src/Signer/Signer.php
+++ b/src/Signer/Signer.php
@@ -6,5 +6,5 @@ interface Signer
 {
     public function signatureHeaderName(): string;
 
-    public function calculateSignature(array $payload, string $secret): string;
+    public function calculateSignature(string $webhookUrl, array $payload, string $secret): string;
 }
diff --git a/src/WebhookCall.php b/src/WebhookCall.php
index a5f74cd..4fa58de 100644
--- a/src/WebhookCall.php
+++ b/src/WebhookCall.php
@@ -220,7 +220,7 @@ protected function getAllHeaders(): array
             return $headers;
         }
 
-        $signature = $this->signer->calculateSignature($this->payload, $this->secret);
+        $signature = $this->signer->calculateSignature($this->callWebhookJob->webhookUrl, $this->payload, $this->secret);
 
         $headers[$this->signer->signatureHeaderName()] = $signature;
 
diff --git a/tests/DefaultSignerTest.php b/tests/DefaultSignerTest.php
index 63e75b4..6c748c3 100644
--- a/tests/DefaultSignerTest.php
+++ b/tests/DefaultSignerTest.php
@@ -11,7 +11,7 @@ public function it_can_calculate_a_signature_for_a_given_payload_and_secret()
     {
         $signer = new DefaultSigner();
 
-        $signature = $signer->calculateSignature(['a' => '1'], 'abc');
+        $signature = $signer->calculateSignature('https://my.app/webhooks', ['a' => '1'], 'abc');
 
         $this->assertEquals(
             '345611a3626cf5e080a7a412184001882ab231b8bdb465dc76dbf709f01f210a',