diff --git a/src/Command/AnalyserRunner.php b/src/Command/AnalyserRunner.php
index c452ba4976d..8e4cf18401e 100644
--- a/src/Command/AnalyserRunner.php
+++ b/src/Command/AnalyserRunner.php
@@ -71,7 +71,7 @@ public function runAnalyser(
 			);
 		}
 
-		$schedule = $this->scheduler->scheduleWork($this->cpuCoreCounter->getNumberOfCpuCores(), $files);
+		$schedule = $this->scheduler->scheduleWork($this->cpuCoreCounter->getNumberOfCpuCores(), $files, $debug);
 		$mainScript = null;
 		if (isset($_SERVER['argv'][0]) && is_file($_SERVER['argv'][0])) {
 			$mainScript = $_SERVER['argv'][0];
diff --git a/src/Parallel/Scheduler.php b/src/Parallel/Scheduler.php
index 879cdcc5f5f..9853a4d394d 100644
--- a/src/Parallel/Scheduler.php
+++ b/src/Parallel/Scheduler.php
@@ -42,10 +42,11 @@ public function __construct(
 	public function scheduleWork(
 		int $cpuCores,
 		array $files,
+		bool $debug
 	): Schedule
 	{
 		$jobs = array_chunk($files, $this->jobSize);
-		$numberOfProcesses = min(
+		$numberOfProcesses = $debug ? 1 : min(
 			max((int) floor(count($jobs) / $this->minimumNumberOfJobsPerProcess), 1),
 			$cpuCores,
 		);