diff --git a/src/Framework/Helpers.php b/src/Framework/Helpers.php
index a18d90c2..7cfb3e11 100644
--- a/src/Framework/Helpers.php
+++ b/src/Framework/Helpers.php
@@ -130,4 +130,25 @@ public static function escapeArg(string $s): string
 			? '"' . str_replace('"', '""', $s) . '"'
 			: escapeshellarg($s);
 	}
+
+
+	/**
+	 * @internal
+	 */
+	public static function prepareTempDir(string $path): string
+	{
+		$real = realpath($path);
+		if ($real === false) {
+			throw new \RuntimeException("Path '$path' does not exist.");
+		} elseif (!is_dir($real) || !is_writable($real)) {
+			throw new \RuntimeException("Path '$real' is not a writable directory.");
+		}
+
+		$path = $real . DIRECTORY_SEPARATOR . 'Tester';
+		if (!is_dir($path) && @mkdir($path) === false && !is_dir($path)) {  // @ - directory may exist
+			throw new \RuntimeException("Cannot create '$path' directory.");
+		}
+
+		return $path;
+	}
 }
diff --git a/src/Runner/CliTester.php b/src/Runner/CliTester.php
index aedf1875..76f6063c 100644
--- a/src/Runner/CliTester.php
+++ b/src/Runner/CliTester.php
@@ -133,7 +133,7 @@ private function loadOptions(): CommandLine
 			'-c' => [CommandLine::Realpath => true],
 			'--watch' => [CommandLine::Repeatable => true, CommandLine::Realpath => true],
 			'--setup' => [CommandLine::Realpath => true],
-			'--temp' => [CommandLine::Realpath => true],
+			'--temp' => [],
 			'paths' => [CommandLine::Repeatable => true, CommandLine::Value => getcwd()],
 			'--debug' => [],
 			'--cider' => [],
@@ -179,8 +179,10 @@ private function loadOptions(): CommandLine
 			} elseif (($real = realpath($temp)) === false) {
 				echo "Note: System temporary directory '$temp' does not exist.\n";
 			} else {
-				$this->options['--temp'] = rtrim($real, DIRECTORY_SEPARATOR);
+				$this->options['--temp'] = Helpers::prepareTempDir($real);
 			}
+		} else {
+			$this->options['--temp'] = Helpers::prepareTempDir($this->options['--temp']);
 		}
 
 		return $cmd;
@@ -218,10 +220,7 @@ private function createRunner(): Runner
 		$runner->paths = $this->options['paths'];
 		$runner->threadCount = max(1, (int) $this->options['-j']);
 		$runner->stopOnFail = $this->options['--stop-on-fail'];
-
-		if ($this->options['--temp'] !== null) {
-			$runner->setTempDirectory($this->options['--temp']);
-		}
+		$runner->setTempDirectory($this->options['--temp']);
 
 		if ($this->stdoutFormat === null) {
 			$runner->outputHandlers[] = new Output\ConsolePrinter(
diff --git a/src/Runner/Runner.php b/src/Runner/Runner.php
index 96aac9f3..6b0d4111 100644
--- a/src/Runner/Runner.php
+++ b/src/Runner/Runner.php
@@ -84,17 +84,6 @@ public function addPhpIniOption(string $name, ?string $value = null): void
 
 	public function setTempDirectory(?string $path): void
 	{
-		if ($path !== null) {
-			if (!is_dir($path) || !is_writable($path)) {
-				throw new \RuntimeException("Path '$path' is not a writable directory.");
-			}
-
-			$path = realpath($path) . DIRECTORY_SEPARATOR . 'Tester';
-			if (!is_dir($path) && @mkdir($path) === false && !is_dir($path)) {  // @ - directory may exist
-				throw new \RuntimeException("Cannot create '$path' directory.");
-			}
-		}
-
 		$this->tempDir = $path;
 		$this->testHandler->setTempDirectory($path);
 	}