diff --git a/src/Converter/Number/GenericNumberConverter.php b/src/Converter/Number/GenericNumberConverter.php
index c85bc3a..b95d5e0 100644
--- a/src/Converter/Number/GenericNumberConverter.php
+++ b/src/Converter/Number/GenericNumberConverter.php
@@ -19,7 +19,7 @@ use Ramsey\Uuid\Math\CalculatorInterface;
 use Ramsey\Uuid\Type\Integer as IntegerObject;
 
 /**
- * GenericNumberConverter uses the provided calculate to convert decimal
+ * GenericNumberConverter uses the provided calculator to convert decimal
  * numbers to and from hexadecimal values
  *
  * @psalm-immutable
diff --git a/src/Type/Integer.php b/src/Type/Integer.php
index 05d420a..540ecbe 100644
--- a/src/Type/Integer.php
+++ b/src/Type/Integer.php
@@ -36,7 +36,7 @@ use function substr;
 final class Integer implements NumberInterface
 {
     /**
-     * @var string
+     * @psalm-var numeric-string
      */
     private $value;
 
@@ -80,7 +80,10 @@ final class Integer implements NumberInterface
             $this->isNegative = true;
         }
 
-        $this->value = $value;
+        /** @psalm-var numeric-string $numericValue */
+        $numericValue = $value;
+
+        $this->value = $numericValue;
     }
 
     public function isNegative(): bool
@@ -88,6 +91,9 @@ final class Integer implements NumberInterface
         return $this->isNegative;
     }
 
+    /**
+     * @psalm-return numeric-string
+     */
     public function toString(): string
     {
         return $this->value;
diff --git a/tests/phpstan-tests.neon b/tests/phpstan-tests.neon
index c31d53e..1973ce3 100644
--- a/tests/phpstan-tests.neon
+++ b/tests/phpstan-tests.neon
@@ -3,7 +3,7 @@ parameters:
     level: max
     paths:
         - .
-    autoload_files:
+    bootstrapFiles:
         - ./phpstan-bootstrap.php
     checkMissingIterableValueType: false
     reportUnmatchedIgnoredErrors: false
diff --git a/tests/phpstan.neon b/tests/phpstan.neon
index 405d2d8..9a01671 100644
--- a/tests/phpstan.neon
+++ b/tests/phpstan.neon
@@ -5,7 +5,7 @@ parameters:
         - ../src
     checkMissingIterableValueType: false
     reportUnmatchedIgnoredErrors: false
-    autoload_files:
+    bootstrapFiles:
         - ./phpstan-bootstrap.php
     ignoreErrors:
         -