diff --git a/src/InputData/FileUploadInputData.php b/src/InputData/FileUploadInputData.php
index c94a50d..4696fab 100644
--- a/src/InputData/FileUploadInputData.php
+++ b/src/InputData/FileUploadInputData.php
@@ -27,7 +27,7 @@ public function __construct(array $files) {
 	 * with [], in which case each value is another array. This function
 	 * normalises the array to the latter.
 	 *
-	 * @param array<string, string|array<string, string>> $files
+	 * @param array<string, string|array<string, string|array<string>>> $files
 	 * @return array<string, array<string, array<string>>>
 	 */
 	protected function normalizeArray(array $files):array {