diff --git a/src/Utils/FileSystem.php b/src/Utils/FileSystem.php
index 14771399f..5402d0fc8 100644
--- a/src/Utils/FileSystem.php
+++ b/src/Utils/FileSystem.php
@@ -24,8 +24,8 @@ class FileSystem
 	 */
 	public static function createDir($dir, $mode = 0777)
 	{
-		if (!is_dir($dir) && !@mkdir($dir, $mode, TRUE)) { // intentionally @; not atomic
-			throw new Nette\IOException("Unable to create directory '$dir'.");
+		if (!is_dir($dir) && !@mkdir($dir, $mode, TRUE) && !is_dir($dir)) { // @ - dir may already exist
+			throw new Nette\IOException("Unable to create directory '$dir'. " . error_get_last()['message']);
 		}
 	}
 
diff --git a/tests/Utils/FileSystem.phpt b/tests/Utils/FileSystem.phpt
index 75be57c11..68a69dbe9 100644
--- a/tests/Utils/FileSystem.phpt
+++ b/tests/Utils/FileSystem.phpt
@@ -21,7 +21,7 @@ test(function () { // createDir
 
 Assert::exception(function () {
 	FileSystem::createDir('');
-}, Nette\IOException::class, "Unable to create directory ''.");
+}, Nette\IOException::class, "Unable to create directory ''.%A%");
 
 
 test(function () { // write + read
@@ -32,7 +32,7 @@ test(function () { // write + read
 
 Assert::exception(function () {
 	FileSystem::write('', 'Hello');
-}, Nette\IOException::class, "Unable to create directory ''.");
+}, Nette\IOException::class, "Unable to create directory ''.%A%");
 
 Assert::exception(function () {
 	FileSystem::read('');