diff --git a/app/Services/Api/V1/ReleaseItemPayloadBuilder.php b/app/Services/Api/V1/ReleaseItemPayloadBuilder.php
index 1fcbb1fd7..dec022c7d 100644
--- a/app/Services/Api/V1/ReleaseItemPayloadBuilder.php
+++ b/app/Services/Api/V1/ReleaseItemPayloadBuilder.php
@@ -124,7 +124,11 @@ final readonly class ReleaseItemPayloadBuilder
         $attributes['grabs'] = $this->value($release, 'grabs');
         $attributes['comments'] = $this->value($release, 'comments');
         $attributes['password'] = $this->value($release, 'passwordstatus');
-        $attributes['usenetdate'] = date(DATE_RSS, strtotime((string) $this->value($release, 'postdate')));
+        $usenetTimestamp = $this->timestamp($this->value($release, 'postdate'))
+            ?? $this->timestamp($this->value($release, 'adddate'));
+        if ($usenetTimestamp !== null) {
+            $attributes['usenetdate'] = date(DATE_RSS, $usenetTimestamp);
+        }
 
         $groupName = $this->value($release, 'group_name');
         if (! empty($groupName)) {
@@ -223,4 +227,19 @@ final readonly class ReleaseItemPayloadBuilder
 
         return null;
     }
+
+    private function timestamp(mixed $value): ?int
+    {
+        if (\is_int($value)) {
+            return $value;
+        }
+
+        if (! \is_string($value) || trim($value) === '') {
+            return null;
+        }
+
+        $timestamp = strtotime($value);
+
+        return $timestamp === false ? null : $timestamp;
+    }
 }
diff --git a/tests/Unit/Api/XMLResponseTest.php b/tests/Unit/Api/XMLResponseTest.php
index eba412a80..13fd86a92 100644
--- a/tests/Unit/Api/XMLResponseTest.php
+++ b/tests/Unit/Api/XMLResponseTest.php
@@ -99,6 +99,21 @@ final class XMLResponseTest extends TestCase
         self::assertStringContainsString('<newznab:attr name="group" value="alt.binaries.testing"/>', $xml);
     }
 
+    public function test_extended_api_falls_back_to_adddate_for_invalid_postdate(): void
+    {
+        $release = $this->release([
+            'postdate' => 'not-a-date',
+        ]);
+
+        $array = $this->response([$release], ['extended' => '1'])->returnArray();
+
+        self::assertIsArray($array);
+        self::assertSame(
+            date(DATE_RSS, strtotime('2026-05-29 12:00:00')),
+            $array['item'][0]['attr']['usenetdate']
+        );
+    }
+
     public function test_api_rows_are_normalized_from_supported_payload_shapes(): void
     {
         $arrayRow = (array) $this->release([