diff --git a/src/Job.php b/src/Job.php
index bd16fc45..c142b0d4 100644
--- a/src/Job.php
+++ b/src/Job.php
@@ -96,6 +96,9 @@ public function setup(): void
 
     public function getSignature(): string
     {
+        if (!$this->URLsToProcess) {
+            return md5(static::class);
+        }
         return md5(implode('-', [static::class, implode('-', array_keys($this->URLsToProcess))]));
     }
 
@@ -104,14 +107,16 @@ public function process(): void
         $chunkSize = $this->getChunkSize();
         $count = 0;
 
-        foreach ($this->URLsToProcess as $url => $priority) {
-            $count += 1;
+        if ($this->URLsToProcess) {
+            foreach ($this->URLsToProcess as $url => $priority) {
+                $count += 1;
 
-            if ($chunkSize > 0 && $count > $chunkSize) {
-                return;
-            }
+                if ($chunkSize > 0 && $count > $chunkSize) {
+                    return;
+                }
 
-            $this->processUrl($url, $priority);
+                $this->processUrl($url, $priority);
+            }
         }
 
         $this->updateCompletedState();
@@ -149,7 +154,7 @@ protected function markUrlAsProcessed(string $url): void
      */
     protected function updateCompletedState(): void
     {
-        if (count($this->URLsToProcess) > 0) {
+        if ($this->URLsToProcess && count($this->URLsToProcess) > 0) {
             return;
         }
 
diff --git a/tests/php/RunDeleteCacheJobTest.php b/tests/php/RunDeleteCacheJobTest.php
new file mode 100644
index 00000000..bfa7519f
--- /dev/null
+++ b/tests/php/RunDeleteCacheJobTest.php
@@ -0,0 +1,42 @@
+<?php
+
+namespace SilverStripe\StaticPublishQueue\Job;
+
+use SilverStripe\Dev\FunctionalTest;
+use Symbiote\QueuedJobs\Services\QueuedJobService;
+
+class RunDeleteCacheJobTest extends FunctionalTest
+{
+    public function testHydrationAffectsSignature()
+    {
+        $job = new DeleteStaticCacheJob();
+        $data = $job->getJobData();
+        $signature = $job->getSignature();
+        $this->assertEmpty($data->jobData);
+        $this->assertFalse($data->isComplete);
+
+        $job->hydrate(['/' => 1], null);
+        $data = $job->getJobData();
+        $this->assertIsObject($data->jobData);
+        $this->assertFalse($data->isComplete);
+        $hydratedSignature = $job->getSignature();
+
+        // hydrating the job should affect the signature
+        $this->assertNotEquals($signature, $hydratedSignature);
+    }
+
+    // test that the job can process regardless of URLsToProcess
+    public function testJobCanComplete()
+    {
+        $job = new DeleteStaticCacheJob();
+        $job->process();
+        $data = $job->getJobData();
+        $this->assertTrue($data->isComplete);
+
+        $job = new DeleteStaticCacheJob();
+        $job->hydrate(['/' => 1], null);
+        $job->process();
+        $data = $job->getJobData();
+        $this->assertTrue($data->isComplete);
+    }
+}