diff --git a/src/NetworkFunction/NetworkUseCase.php b/src/NetworkFunction/NetworkUseCase.php
index dd32476..42a9736 100644
--- a/src/NetworkFunction/NetworkUseCase.php
+++ b/src/NetworkFunction/NetworkUseCase.php
@@ -101,7 +101,7 @@ private function isPageKey( ?string $key ): bool {
 
 	/**
 	 * @param string $pages
-	 * @param string $delimiter
+	 * @param non-empty-string $delimiter
 	 * @return string[]
 	 */
 	private function pagesStringToArray( string $pages, string $delimiter ): array {