diff --git a/src/RobotLoader/RobotLoader.php b/src/RobotLoader/RobotLoader.php
index d214e07..938760c 100644
--- a/src/RobotLoader/RobotLoader.php
+++ b/src/RobotLoader/RobotLoader.php
@@ -397,6 +397,9 @@ public function setAutoRefresh(bool $on = true): static
 	 */
 	public function setTempDirectory(string $dir): static
 	{
+		if (!FileSystem::isAbsolute($dir)) {
+			throw new Nette\InvalidArgumentException("Temporary directory must be absolute, '$dir' given.");
+		}
 		FileSystem::createDir($dir);
 		$this->tempDirectory = $dir;
 		return $this;