diff --git a/composer.json b/composer.json
index 925d93af..d7a1e8c4 100644
--- a/composer.json
+++ b/composer.json
@@ -47,7 +47,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "5.2-dev"
+            "dev-master": "5.3-dev"
         }
     }
 }
diff --git a/src/Validator.php b/src/Validator.php
index dffe4626..0c04ab62 100644
--- a/src/Validator.php
+++ b/src/Validator.php
@@ -161,7 +161,7 @@ static function (string $value) use ($regex) {
      *
      * @return \Dotenv\Validator
      */
-    private function assert(callable $callback, string $message)
+    public function assert(callable $callback, string $message)
     {
         $failing = [];
 
@@ -193,7 +193,7 @@ private function assert(callable $callback, string $message)
      *
      * @return \Dotenv\Validator
      */
-    private function assertNullable(callable $callback, string $message)
+    public function assertNullable(callable $callback, string $message)
     {
         return $this->assert(
             static function (?string $value) use ($callback) {