diff --git a/tests/OtherObject/AllTest.php b/tests/OtherObject/AllTest.php
index 95d8507..4f1f8de 100644
--- a/tests/OtherObject/AllTest.php
+++ b/tests/OtherObject/AllTest.php
@@ -421,6 +421,6 @@ public static function getDoublePrecisionFloatObject(): Iterator
 
     private static function bitsToByteString(string $data, int $length): string
     {
-        return mb_str_pad(BigInteger::fromBase($data, 2)->toBytes(false), $length, "\0", STR_PAD_LEFT);
+        return str_pad(BigInteger::fromBase($data, 2)->toBytes(false), $length, "\0", STR_PAD_LEFT);
     }
 }