diff --git a/src/Users/user.php b/src/Users/user.php
index e0fc1cee..d455f4eb 100644
--- a/src/Users/user.php
+++ b/src/Users/user.php
@@ -14,7 +14,8 @@ define('MSZ_PERM_USER_MANAGE_REPORTS', 1 << 23);
 define('MSZ_PERM_USER_MANAGE_RESTRICTIONS', 1 << 24);
 define('MSZ_PERM_USER_MANAGE_BLACKLISTS', 1 << 25);
 
-define('MSZ_USERS_PASSWORD_HASH_ALGO', PASSWORD_ARGON2I);
+// falls back to bcrypt if argon2i isn't available, thanks travis ci
+define('MSZ_USERS_PASSWORD_HASH_ALGO', defined('PASSWORD_ARGON2I') ? PASSWORD_ARGON2I : PASSWORD_BCRYPT);
 
 function user_create(
     string $username,