diff --git a/src/Illuminate/Bus/DatabaseBatchRepository.php b/src/Illuminate/Bus/DatabaseBatchRepository.php
index 842e76438769..2c5461512818 100644
--- a/src/Illuminate/Bus/DatabaseBatchRepository.php
+++ b/src/Illuminate/Bus/DatabaseBatchRepository.php
@@ -141,7 +141,7 @@ public function decrementPendingJobs(string $batchId, string $jobId)
             return [
                 'pending_jobs' => $batch->pending_jobs - 1,
                 'failed_jobs' => $batch->failed_jobs,
-                'failed_job_ids' => json_encode(array_values(array_diff(json_decode($batch->failed_job_ids, true), [$jobId]))),
+                'failed_job_ids' => json_encode(array_values(array_diff((array) json_decode($batch->failed_job_ids, true), [$jobId]))),
             ];
         });
 
@@ -164,7 +164,7 @@ public function incrementFailedJobs(string $batchId, string $jobId)
             return [
                 'pending_jobs' => $batch->pending_jobs,
                 'failed_jobs' => $batch->failed_jobs + 1,
-                'failed_job_ids' => json_encode(array_values(array_unique(array_merge(json_decode($batch->failed_job_ids, true), [$jobId])))),
+                'failed_job_ids' => json_encode(array_values(array_unique(array_merge((array) json_decode($batch->failed_job_ids, true), [$jobId])))),
             ];
         });