diff --git a/src/View/Helper/ThumbHelper.php b/src/View/Helper/ThumbHelper.php
index 18a3297..8735046 100644
--- a/src/View/Helper/ThumbHelper.php
+++ b/src/View/Helper/ThumbHelper.php
@@ -106,8 +106,9 @@ public function status(
             return static::NOT_ACCEPTABLE;
         }
         try {
+            $id = !empty($imageId) ? intval($imageId) : null;
             $apiClient = ApiClientProvider::getApiClient();
-            $response = $apiClient->thumbs($imageId, (array)$options);
+            $response = $apiClient->thumbs($id, (array)$options);
             if (empty($response['meta']['thumbnails'][0])) {
                 return static::NOT_AVAILABLE;
             }
@@ -137,13 +138,13 @@ public function status(
     /**
      * Obtain thumbnail using API thumbs.
      *
-     * @param int $imageId The image ID.
+     * @param string|int $imageId The image ID.
      * @param array|null $options The thumbs options.
      * @return string|int The url if available, the status code otherwise (see Thumb constants).
      */
-    public function url(int $imageId, ?array $options): string|int
+    public function url(string|int $imageId, ?array $options): string|int
     {
-        $url = null;
+        $url = '';
         $status = $this->status($imageId, $options, $url);
         if ($status === static::OK) {
             return $url;
@@ -212,13 +213,14 @@ public function getUrl(?array $image, array $options = []): string
 
             return '';
         }
+        $imageId = intval($image['id']);
         $thumbHash = md5((string)Hash::get($image, 'meta.media_url') . json_encode($options));
-        $key = sprintf('%d_%s', $image['id'], $thumbHash);
+        $key = sprintf('%d_%s', $imageId, $thumbHash);
 
         return (string)Cache::remember(
             $key,
-            function () use ($image, $options) {
-                return $this->url($image['id'], $options);
+            function () use ($imageId, $options) {
+                return $this->url($imageId, $options);
             },
             $this->getConfig('cache'),
         );
diff --git a/tests/TestCase/View/Helper/ThumbHelperTest.php b/tests/TestCase/View/Helper/ThumbHelperTest.php
index 29b2ccd..44de21e 100644
--- a/tests/TestCase/View/Helper/ThumbHelperTest.php
+++ b/tests/TestCase/View/Helper/ThumbHelperTest.php
@@ -196,6 +196,13 @@ public static function urlProvider(): array
                 ],
                 ThumbHelper::NOT_AVAILABLE,
             ],
+            'thumb with id string' => [
+                [
+                    'id' => '-1',
+                    'options' => null, // use default preset
+                ],
+                ThumbHelper::NOT_AVAILABLE,
+            ],
         ];
     }