diff --git a/lib/PhpParser/Node/Scalar/DNumber.php b/lib/PhpParser/Node/Scalar/DNumber.php
index ae9cb2f..400f446 100644
--- a/lib/PhpParser/Node/Scalar/DNumber.php
+++ b/lib/PhpParser/Node/Scalar/DNumber.php
@@ -25,6 +25,8 @@ class DNumber extends Scalar
     }
 
     /**
+     * @internal
+     *
      * Parses a DNUMBER token like PHP would.
      *
      * @param string $str A string number
diff --git a/lib/PhpParser/Node/Scalar/LNumber.php b/lib/PhpParser/Node/Scalar/LNumber.php
index 63a3d9d..dccc775 100644
--- a/lib/PhpParser/Node/Scalar/LNumber.php
+++ b/lib/PhpParser/Node/Scalar/LNumber.php
@@ -25,6 +25,8 @@ class LNumber extends Scalar
     }
 
     /**
+     * @internal
+     *
      * Parses an LNUMBER token (dec, hex, oct and bin notations) like PHP would.
      *
      * @param string $str A string number
diff --git a/lib/PhpParser/Node/Scalar/String.php b/lib/PhpParser/Node/Scalar/String.php
index a5484e0..1af3806 100644
--- a/lib/PhpParser/Node/Scalar/String.php
+++ b/lib/PhpParser/Node/Scalar/String.php
@@ -36,6 +36,8 @@ class String extends Scalar
     }
 
     /**
+     * @internal
+     *
      * Parses a string token.
      *
      * @param string $str String token content
@@ -60,6 +62,8 @@ class String extends Scalar
     }
 
     /**
+     * @internal
+     *
      * Parses escape sequences in strings (all string types apart from single quoted).
      *
      * @param string      $str   String without quotes
@@ -79,7 +83,7 @@ class String extends Scalar
         );
     }
 
-    public static function parseCallback($matches) {
+    private static function parseCallback($matches) {
         $str = $matches[1];
 
         if (isset(self::$replacements[$str])) {
@@ -92,6 +96,8 @@ class String extends Scalar
     }
 
     /**
+     * @internal
+     *
      * Parses a constant doc string.
      *
      * @param string $startToken Doc string start token content (<<<SMTHG)
diff --git a/lib/PhpParser/Node/Stmt/Class_.php b/lib/PhpParser/Node/Stmt/Class_.php
index d4fdcd8..3ed3645 100644
--- a/lib/PhpParser/Node/Stmt/Class_.php
+++ b/lib/PhpParser/Node/Stmt/Class_.php
@@ -83,6 +83,9 @@ class Class_ extends Node\Stmt
         return $methods;
     }
 
+    /**
+     * @internal
+     */
     public static function verifyModifier($a, $b) {
         if ($a & 7 && $b & 7) {
             throw new Error('Multiple access type modifiers are not allowed');