diff --git a/composer.json b/composer.json
index e787111..aa0a9d5 100644
--- a/composer.json
+++ b/composer.json
@@ -19,11 +19,12 @@
     }
   ],
   "require": {
-    "php": "^7.2",
+    "php": "^7.2 || ^7.3",
     "ext-sodium": "*",
     "doctrine/annotations": "^1.6",
     "doctrine/orm": "^2.6",
     "paragonie/halite": "^4.4",
+    "paragonie/hidden-string": "^1.0",
     "paragonie/ciphersweet": "^1.7.0",
     "zendframework/zend-modulemanager": "^2.8",
     "zendframework/zend-servicemanager": "^2.7.8 || ^3.3",