diff --git a/tests/unicode_characters.aer b/tests/unicode_characters.aer
index 5771fca..6435237 100644
--- a/tests/unicode_characters.aer
+++ b/tests/unicode_characters.aer
@@ -38,7 +38,7 @@ class Unicode {
 		if($to_uni) {
 			$str = strtr($str, $cp);
 		} else {
-			foreach($c in $cp) {
+			foreach(string $c in $cp) {
 				$cpp[$c] = array_search($c, $cp);
 			}
 			$str = strtr($str, $cpp);