diff --git a/src/Framework/Environment.php b/src/Framework/Environment.php
index e9d9f8d4..d0c7a92c 100644
--- a/src/Framework/Environment.php
+++ b/src/Framework/Environment.php
@@ -27,9 +27,6 @@ class Environment
 	/** Thread number when run tests in multi threads */
 	public const THREAD = 'NETTE_TESTER_THREAD';
 
-	/** @var bool  used for debugging Tester itself */
-	public static $debugMode = true;
-
 	/** @var bool */
 	public static $checkAssertions = false;
 
@@ -125,7 +122,7 @@ public static function handleException(\Throwable $e): void
 	{
 		self::removeOutputBuffers();
 		self::$checkAssertions = false;
-		echo self::$debugMode ? Dumper::dumpException($e) : "\nError: {$e->getMessage()}\n";
+		echo Dumper::dumpException($e);
 		exit($e instanceof AssertException ? Runner\Job::CODE_FAIL : Runner\Job::CODE_ERROR);
 	}
 
diff --git a/src/Runner/CliTester.php b/src/Runner/CliTester.php
index 99985c49..3cee49e4 100644
--- a/src/Runner/CliTester.php
+++ b/src/Runner/CliTester.php
@@ -25,6 +25,9 @@ class CliTester
 	/** @var PhpInterpreter */
 	private $interpreter;
 
+	/** @var bool */
+	private $debugMode = true;
+
 
 	public function run(): ?int
 	{
@@ -34,7 +37,7 @@ public function run(): ?int
 		ob_start();
 		$cmd = $this->loadOptions();
 
-		Environment::$debugMode = (bool) $this->options['--debug'];
+		$this->debugMode = (bool) $this->options['--debug'];
 		if (isset($this->options['--colors'])) {
 			Environment::$useColors = (bool) $this->options['--colors'];
 		} elseif (in_array($this->options['-o'], ['tap', 'junit'], true)) {
@@ -300,7 +303,7 @@ private function setupErrors(): void
 	private function displayException(\Throwable $e): void
 	{
 		echo "\n";
-		echo Environment::$debugMode
+		echo $this->debugMode
 			? Dumper::dumpException($e)
 			: Dumper::color('white/red', 'Error: ' . $e->getMessage());
 		echo "\n";