diff --git a/tests/Tracy/Debugger.log().error.phpt b/tests/Tracy/Debugger.log().error.phpt
index 8951e5670..c9f24601b 100644
--- a/tests/Tracy/Debugger.log().error.phpt
+++ b/tests/Tracy/Debugger.log().error.phpt
@@ -19,11 +19,11 @@ Assert::exception(function () {
 
 
 // no error
-Debugger::$logDirectory = TEMP_DIR;
+Debugger::$logDirectory = getTempDir();
 Debugger::log('Hello');
 
 
-Debugger::$logDirectory = TEMP_DIR . '/unknown';
+Debugger::$logDirectory = getTempDir() . '/unknown';
 Assert::exception(function () {
 	Debugger::log('Hello');
 }, 'RuntimeException', "Logging directory '%a%' is not found or is not directory.");
diff --git a/tests/Tracy/Debugger.log().samefile.phpt b/tests/Tracy/Debugger.log().samefile.phpt
index 70afe81a9..212825168 100644
--- a/tests/Tracy/Debugger.log().samefile.phpt
+++ b/tests/Tracy/Debugger.log().samefile.phpt
@@ -14,7 +14,7 @@ require __DIR__ . '/../bootstrap.php';
 
 
 // Setup environment
-Debugger::$logDirectory = TEMP_DIR;
+Debugger::$logDirectory = getTempDir();
 
 
 function foo($fp)
@@ -24,9 +24,9 @@ function foo($fp)
 
 
 for ($i = 0; $i < 3; $i++) {
-	$path = TEMP_DIR . "/$i";
+	$path = getTempDir() . "/$i";
 	try {
-		$files[] = $file = fopen(TEMP_DIR . "/$i", 'w');
+		$files[] = $file = fopen(getTempDir() . "/$i", 'w');
 		foo($file);
 	} catch (Exception $e) {
 		$name[] = Debugger::log($e);
diff --git a/tests/Tracy/Debugger.logSeverity.E_NOTICE.development.phpt b/tests/Tracy/Debugger.logSeverity.E_NOTICE.development.phpt
index 0d641dfa2..0292154a7 100644
--- a/tests/Tracy/Debugger.logSeverity.E_NOTICE.development.phpt
+++ b/tests/Tracy/Debugger.logSeverity.E_NOTICE.development.phpt
@@ -14,10 +14,10 @@ require __DIR__ . '/../bootstrap.php';
 
 
 // Setup environment
-Debugger::enable(Debugger::DEVELOPMENT, TEMP_DIR);
+Debugger::enable(Debugger::DEVELOPMENT, getTempDir());
 Debugger::$logSeverity = E_NOTICE;
 
 $variable = $missingVariable;
 
-Assert::count(0, glob(TEMP_DIR . '/exception*.html'));
-Assert::count(0, glob(TEMP_DIR . '/error.log'));
+Assert::count(0, glob(getTempDir() . '/exception*.html'));
+Assert::count(0, glob(getTempDir() . '/error.log'));
diff --git a/tests/Tracy/Debugger.logSeverity.E_NOTICE.phpt b/tests/Tracy/Debugger.logSeverity.E_NOTICE.phpt
index 560c4b968..647857f35 100644
--- a/tests/Tracy/Debugger.logSeverity.E_NOTICE.phpt
+++ b/tests/Tracy/Debugger.logSeverity.E_NOTICE.phpt
@@ -14,10 +14,10 @@ require __DIR__ . '/../bootstrap.php';
 
 
 // Setup environment
-Debugger::enable(Debugger::PRODUCTION, TEMP_DIR);
+Debugger::enable(Debugger::PRODUCTION, getTempDir());
 Debugger::$logSeverity = E_NOTICE;
 
 $variable = $missingVariable;
 
-Assert::count(1, glob(TEMP_DIR . '/error*.html'));
-Assert::count(1, glob(TEMP_DIR . '/error.log'));
+Assert::count(1, glob(getTempDir() . '/error*.html'));
+Assert::count(1, glob(getTempDir() . '/error.log'));
diff --git a/tests/Tracy/Debugger.logging.error.phpt b/tests/Tracy/Debugger.logging.error.phpt
index bd6d6c329..d10d9bf2b 100644
--- a/tests/Tracy/Debugger.logging.error.phpt
+++ b/tests/Tracy/Debugger.logging.error.phpt
@@ -19,7 +19,7 @@ require __DIR__ . '/../bootstrap.php';
 // Setup environment
 $_SERVER['HTTP_HOST'] = 'nette.org';
 
-Debugger::$logDirectory = TEMP_DIR;
+Debugger::$logDirectory = getTempDir();
 
 Debugger::getLogger()->mailer = function () {};
 
diff --git a/tests/Tracy/Debugger.logging.warnings.phpt b/tests/Tracy/Debugger.logging.warnings.phpt
index 1b84f4abe..6e7f42283 100644
--- a/tests/Tracy/Debugger.logging.warnings.phpt
+++ b/tests/Tracy/Debugger.logging.warnings.phpt
@@ -16,7 +16,7 @@ require __DIR__ . '/../bootstrap.php';
 // Setup environment
 $_SERVER['HTTP_HOST'] = 'nette.org';
 
-$logDirectory = TEMP_DIR;
+$logDirectory = getTempDir();
 
 Debugger::getLogger()->mailer = function () {};
 
diff --git a/tests/Tracy/Logger.extensible.phpt b/tests/Tracy/Logger.extensible.phpt
index 6226fac3b..8143f12d3 100644
--- a/tests/Tracy/Logger.extensible.phpt
+++ b/tests/Tracy/Logger.extensible.phpt
@@ -37,7 +37,7 @@ class CustomLogger extends Logger
 
 
 test(function () {
-	$logger = new CustomLogger(TEMP_DIR);
+	$logger = new CustomLogger(getTempDir());
 	$logger->log(new Exception('First'), 'a');
 
 	Assert::match('a', $logger->collector[0][0]);
@@ -47,7 +47,7 @@ test(function () {
 });
 
 test(function () {
-	$logger = new CustomLogger(TEMP_DIR);
+	$logger = new CustomLogger(getTempDir());
 	$logger->log('message', 'b');
 
 	Assert::match('b', $logger->collector[0][0]);
diff --git a/tests/Tracy/Logger.log().errors.phpt b/tests/Tracy/Logger.log().errors.phpt
index 31bc82729..311391c81 100644
--- a/tests/Tracy/Logger.log().errors.phpt
+++ b/tests/Tracy/Logger.log().errors.phpt
@@ -13,18 +13,18 @@ use Tracy\Logger;
 require __DIR__ . '/../bootstrap.php';
 
 
-$logger = new Logger(TEMP_DIR);
+$logger = new Logger(getTempDir());
 $logger->log('Hello'); // no error
 
 
 Assert::exception(function () {
-	$logger = new Logger(TEMP_DIR . '/unknown');
+	$logger = new Logger(getTempDir() . '/unknown');
 	$logger->log('Hello');
 }, 'RuntimeException', "Logging directory '%a%' is not found or is not directory.");
 
 
 Assert::exception(function () {
-	$logger = new Logger(TEMP_DIR);
-	mkdir(TEMP_DIR . '/test.log');
+	$logger = new Logger(getTempDir());
+	mkdir(getTempDir() . '/test.log');
 	$logger->log('Hello', 'test');
 }, 'RuntimeException', "Unable to write to log file '%a%'. Is directory writable?");
diff --git a/tests/Tracy/Logger.log().phpt b/tests/Tracy/Logger.log().phpt
index 7dfa867b1..1c47d0ba5 100644
--- a/tests/Tracy/Logger.log().phpt
+++ b/tests/Tracy/Logger.log().phpt
@@ -15,7 +15,7 @@ require __DIR__ . '/../bootstrap.php';
 
 test(function () {
 	$e = new Exception('First');
-	$logger = new Logger(TEMP_DIR);
+	$logger = new Logger(getTempDir());
 	$logger->log($e, 'a');
 	Assert::match('[%a%] Exception: First in %a%:%d% %A%', file_get_contents($logger->directory . '/a.log'));
 });
@@ -24,31 +24,31 @@ test(function () {
 	$e = new Exception('First');
 	$e = new InvalidArgumentException('Second', 0, $e);
 	$e = new RuntimeException('Third', 0, $e);
-	$logger = new Logger(TEMP_DIR);
+	$logger = new Logger(getTempDir());
 	$logger->log($e, 'b');
 	Assert::match('[%a%] RuntimeException: Third in %a%:%d% caused by InvalidArgumentException: Second in %a%:%d% caused by Exception: First in %a%:%d% %A%', file_get_contents($logger->directory . '/b.log'));
 });
 
 test(function () {
-	$logger = new Logger(TEMP_DIR);
+	$logger = new Logger(getTempDir());
 	$logger->log(new ErrorException('Msg', 0, E_ERROR, __FILE__, __LINE__), 'c');
 	Assert::match('[%a%] Fatal Error: Msg in %a%Logger.log().phpt:%d%  @  CLI (PID: %d%): %a%  @@  c-%a%.html', file_get_contents($logger->directory . '/c.log'));
 });
 
 test(function () {
-	$logger = new Logger(TEMP_DIR);
+	$logger = new Logger(getTempDir());
 	$logger->log(new ErrorException('Msg', 0, E_WARNING, __FILE__, __LINE__), 'd');
 	Assert::match('[%a%] Warning: Msg in %a%Logger.log().phpt:%d%  @  CLI (PID: %d%): %a%  @@  d-%a%.html', file_get_contents($logger->directory . '/d.log'));
 });
 
 test(function () {
-	$logger = new Logger(TEMP_DIR);
+	$logger = new Logger(getTempDir());
 	$logger->log(new ErrorException('Msg', 0, E_COMPILE_ERROR, __FILE__, __LINE__), 'e');
 	Assert::match('[%a%] Compile Error: Msg in %a%Logger.log().phpt:%d%  @  CLI (PID: %d%): %a%  @@  e-%a%.html', file_get_contents($logger->directory . '/e.log'));
 });
 
 test(function () {
-	$logger = new Logger(TEMP_DIR);
+	$logger = new Logger(getTempDir());
 	$logger->log(new ErrorException('Msg', 0, E_NOTICE, __FILE__, __LINE__), 'f');
 	Assert::match('[%a%] Notice: Msg in %a%Logger.log().phpt:%d%  @  CLI (PID: %d%): %a%  @@  f-%a%.html', file_get_contents($logger->directory . '/f.log'));
 });
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index d443f15ca..8733d39bb 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -16,12 +16,7 @@
 date_default_timezone_set('Europe/Prague');
 ini_set('serialize_precision', '14');
 $_GET = $_POST = $_COOKIE = [];
-
-
-// create temporary directory
-define('TEMP_DIR', __DIR__ . '/tmp/' . getmypid());
-@mkdir(dirname(TEMP_DIR)); // @ - directory may already exist
-Tester\Helpers::purge(TEMP_DIR);
+define('USER_CONST', 1);
 
 
 if (extension_loaded('xdebug')) {
@@ -29,6 +24,27 @@
 }
 
 
+function getTempDir(): string
+{
+	$dir = __DIR__ . '/tmp/' . getmypid();
+
+	if (empty($GLOBALS['\\lock'])) {
+		// garbage collector
+		$GLOBALS['\\lock'] = $lock = fopen(__DIR__ . '/lock', 'w');
+		if (rand(0, 100)) {
+			flock($lock, LOCK_SH);
+			@mkdir(dirname($dir));
+		} elseif (flock($lock, LOCK_EX)) {
+			Tester\Helpers::purge(dirname($dir));
+		}
+
+		@mkdir($dir);
+	}
+
+	return $dir;
+}
+
+
 function test(\Closure $function): void
 {
 	$function();