diff --git a/src/Command/FixerApplication.php b/src/Command/FixerApplication.php
index 07b18dfff7..83cf1f5446 100644
--- a/src/Command/FixerApplication.php
+++ b/src/Command/FixerApplication.php
@@ -237,6 +237,7 @@ private function getFixerProcess(OutputInterface $output, int $serverPort): Proc
 		}
 
 		$env = getenv();
+		$env['PHPSTAN_PRO_TMP_DIR'] = $this->fixerTmpDir;
 		$forcedPort = $_SERVER['PHPSTAN_PRO_WEB_PORT'] ?? null;
 		if ($forcedPort !== null) {
 			$env['PHPSTAN_PRO_WEB_PORT'] = $_SERVER['PHPSTAN_PRO_WEB_PORT'];