diff --git a/src/IO/Filter/Cipher/WinZipAes/WinZipAesEncryptionStreamFilter.php b/src/IO/Filter/Cipher/WinZipAes/WinZipAesEncryptionStreamFilter.php
index d7054fd..24fe5cf 100644
--- a/src/IO/Filter/Cipher/WinZipAes/WinZipAesEncryptionStreamFilter.php
+++ b/src/IO/Filter/Cipher/WinZipAes/WinZipAesEncryptionStreamFilter.php
@@ -89,6 +89,7 @@ class WinZipAesEncryptionStreamFilter extends \php_user_filter
                 if ($winZipExtra === null) {
                     throw new RuntimeException('$winZipExtra is null');
                 }
+                /** @psalm-var positive-int $saltSize */
                 $saltSize = $winZipExtra->getSaltSize();
 
                 try {