diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 7df0721..c92fc1c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: [ '7.4', '8.0', '8.1', '8.2', '8.3', '8.4' ]
+        php: [ '8.1', '8.2', '8.3', '8.4' ]
         os: [ ubuntu-latest, macos-latest, windows-latest ]
         stability: [ prefer-lowest, prefer-stable ]
     steps:
diff --git a/composer.json b/composer.json
index bde465d..066bfb0 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,7 @@
     "require": {
         "php": "^8.1",
         "ext-spl": "*",
-        "phplrt/lexer": "^4.0"
+        "phplrt/lexer": "^3.7"
     },
     "autoload": {
         "psr-4": {
@@ -38,8 +38,8 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "4.x-dev",
-            "dev-main": "4.x-dev"
+            "dev-master": "3.x-dev",
+            "dev-main": "3.x-dev"
         }
     },
     "config": {
diff --git a/src/ArrayBuffer.php b/src/ArrayBuffer.php
index 244335a..91d2b53 100644
--- a/src/ArrayBuffer.php
+++ b/src/ArrayBuffer.php
@@ -45,7 +45,7 @@ private function iterableToArray(iterable $tokens): array
         return $tokens;
     }
 
-    public function seek(mixed $offset): void
+    public function seek($offset): void
     {
         if ($offset < $this->initial) {
             throw new \OutOfRangeException(
diff --git a/src/Buffer.php b/src/Buffer.php
index 411b254..ece21f7 100644
--- a/src/Buffer.php
+++ b/src/Buffer.php
@@ -51,7 +51,7 @@ public function rewind(): void
         $this->seek($this->initial);
     }
 
-    public function seek(mixed $offset): void
+    public function seek($offset): void
     {
         \assert($offset >= 0);
 
diff --git a/src/BufferInterface.php b/src/BufferInterface.php
index a8977a0..c69ebba 100644
--- a/src/BufferInterface.php
+++ b/src/BufferInterface.php
@@ -20,7 +20,7 @@ interface BufferInterface extends \SeekableIterator
      *
      * @param int<0, max> $offset
      */
-    public function seek(mixed $offset): void;
+    public function seek($offset): void;
 
     /**
      * Return the current token.
diff --git a/src/ExtrusiveBuffer.php b/src/ExtrusiveBuffer.php
index 40a8927..5e96eab 100644
--- a/src/ExtrusiveBuffer.php
+++ b/src/ExtrusiveBuffer.php
@@ -20,16 +20,23 @@ class ExtrusiveBuffer extends LazyBuffer
      */
     public const BUFFER_DEFAULT_SIZE = 100;
 
+    /**
+     * @var int<1, max>
+     */
+    private int $size;
+
     /**
      * @param iterable<TokenInterface> $stream
      * @param int<1, max> $size
      */
     public function __construct(
         iterable $stream,
-        private int $size = self::BUFFER_DEFAULT_SIZE
+        int $size = self::BUFFER_DEFAULT_SIZE
     ) {
+        $this->size = $size;
+
         /** @psalm-suppress RedundantCondition */
-        assert($this->size > 0, 'Buffer size must be greater than 0, but ' . $this->size . ' passed');
+        assert($this->size > 0, 'Buffer size must be greater than 0, but ' . $size . ' passed');
 
         parent::__construct($stream);
     }
@@ -42,7 +49,7 @@ public function getBufferSize(): int
         return $this->size;
     }
 
-    public function seek(mixed $offset): void
+    public function seek($offset): void
     {
         if ($offset < \array_key_first($this->buffer)) {
             $message = \sprintf(self::ERROR_BUFFER_MEMORY_ALREADY_FREED, $offset, $this->size);
diff --git a/src/LazyBuffer.php b/src/LazyBuffer.php
index 5d20c6b..9c5ac3f 100644
--- a/src/LazyBuffer.php
+++ b/src/LazyBuffer.php
@@ -54,7 +54,7 @@ public function getBufferCurrentSize(): int
         return \count($this->buffer);
     }
 
-    public function seek(mixed $offset): void
+    public function seek($offset): void
     {
         if ($offset < $this->initial) {
             throw new \OutOfRangeException(
diff --git a/src/MutableBuffer.php b/src/MutableBuffer.php
index e6dc2f3..0de7d9f 100644
--- a/src/MutableBuffer.php
+++ b/src/MutableBuffer.php
@@ -10,14 +10,17 @@
  */
 class MutableBuffer implements BufferInterface
 {
+    private BufferInterface $parent;
+
     /**
      * @var array<int<0, max>, TokenInterface>
      */
     private array $overrides = [];
 
-    public function __construct(
-        private BufferInterface $parent,
-    ) {}
+    public function __construct(BufferInterface $parent)
+    {
+        $this->parent = $parent;
+    }
 
     /**
      * @param int<0, max> $offset
@@ -51,7 +54,7 @@ private function poll(int $offset): TokenInterface
         }
     }
 
-    public function seek(mixed $offset): void
+    public function seek($offset): void
     {
         $this->parent->seek($offset);
     }