diff --git a/src/EncoderProvider.php b/src/EncoderProvider.php
index 76b709a..b88348c 100644
--- a/src/EncoderProvider.php
+++ b/src/EncoderProvider.php
@@ -22,22 +22,27 @@ final class EncoderProvider implements ResetInterface
     public const ENCODINGS = [
         'r50k_base' => [
             'vocab' => 'https://openaipublic.blob.core.windows.net/encodings/r50k_base.tiktoken',
+            'hash' => '306cd27f03c1a714eca7108e03d66b7dc042abe8c258b44c199a7ed9838dd930',
             'pat' => '/\'s|\'t|\'re|\'ve|\'m|\'ll|\'d| ?\p{L}+| ?\p{N}+| ?[^\s\p{L}\p{N}]+|\s+(?!\S)|\s+/u',
         ],
         'p50k_base' => [
             'vocab' => 'https://openaipublic.blob.core.windows.net/encodings/p50k_base.tiktoken',
+            'hash' => '94b5ca7dff4d00767bc256fdd1b27e5b17361d7b8a5f968547f9f23eb70d2069',
             'pat' => '/\'s|\'t|\'re|\'ve|\'m|\'ll|\'d| ?\p{L}+| ?\p{N}+| ?[^\s\p{L}\p{N}]+|\s+(?!\S)|\s+/u',
         ],
         'p50k_edit' => [
             'vocab' => 'https://openaipublic.blob.core.windows.net/encodings/p50k_base.tiktoken',
+            'hash' => '94b5ca7dff4d00767bc256fdd1b27e5b17361d7b8a5f968547f9f23eb70d2069',
             'pat' => '/\'s|\'t|\'re|\'ve|\'m|\'ll|\'d| ?\p{L}+| ?\p{N}+| ?[^\s\p{L}\p{N}]+|\s+(?!\S)|\s+/u',
         ],
         'cl100k_base' => [
             'vocab' => 'https://openaipublic.blob.core.windows.net/encodings/cl100k_base.tiktoken',
+            'hash' => '223921b76ee99bde995b7ff738513eef100fb51d18c93597a113bcffe865b2a7',
             'pat' => '/(?i:\'s|\'t|\'re|\'ve|\'m|\'ll|\'d)|[^\r\n\p{L}\p{N}]?\p{L}+|\p{N}{1,3}| ?[^\s\p{L}\p{N}]+[\r\n]*|\s*[\r\n]+|\s+(?!\S)|\s+/u',
         ],
         'o200k_base' => [
             'vocab' => 'https://openaipublic.blob.core.windows.net/encodings/o200k_base.tiktoken',
+            'hash' => '446a9538cb6c348e3516120d7c08b09f57c36495e2acfffe59a5bf8b0cfb1a2d',
             'pat' => '/[^\r\n\p{L}\p{N}]?[\p{Lu}\p{Lt}\p{Lm}\p{Lo}\p{M}]*[\p{Ll}\p{Lm}\p{Lo}\p{M}]+(?i:\'s|\'t|\'re|\'ve|\'m|\'ll|\'d)?|[^\r\n\p{L}\p{N}]?[\p{Lu}\p{Lt}\p{Lm}\p{Lo}\p{M}]+[\p{Ll}\p{Lm}\p{Lo}\p{M}]*(?i:\'s|\'t|\'re|\'ve|\'m|\'ll|\'d)?|\p{N}{1,3}| ?[^\s\p{L}\p{N}]+[\r\n\/]*|\s*[\r\n]+|\s+(?!\S)|\s+/u',
         ],
     ];
diff --git a/src/Vocab/Loader/DefaultVocabLoader.php b/src/Vocab/Loader/DefaultVocabLoader.php
index 41bb796..cd007ae 100644
--- a/src/Vocab/Loader/DefaultVocabLoader.php
+++ b/src/Vocab/Loader/DefaultVocabLoader.php
@@ -12,10 +12,11 @@
 use function fclose;
 use function file_exists;
 use function fopen;
+use function hash_equals;
+use function hash_file;
 use function is_dir;
 use function is_writable;
 use function mkdir;
-use function preg_match;
 use function sha1;
 use function sprintf;
 use function stream_copy_to_stream;
@@ -28,16 +29,12 @@ public function __construct(private string|null $cacheDir = null)
     {
     }
 
-    public function load(string $uri): Vocab
+    public function load(string $uri, string|null $checksum = null): Vocab
     {
-        if ($this->cacheDir !== null && preg_match('@^https?://@i', $uri)) {
-            $cacheFile = $this->cacheDir . DIRECTORY_SEPARATOR . sha1($uri);
-        } else {
-            $cacheFile = null;
-        }
+        $cacheFile = $this->cacheDir !== null ? $this->cacheDir . DIRECTORY_SEPARATOR . sha1($uri) : null;
 
         if ($cacheFile !== null) {
-            if (file_exists($cacheFile)) {
+            if (file_exists($cacheFile) && $this->checkHash($cacheFile, $checksum)) {
                 return Vocab::fromFile($cacheFile);
             }
 
@@ -83,4 +80,19 @@ public function load(string $uri): Vocab
             fclose($stream);
         }
     }
+
+    private function checkHash(string $filename, string|null $expectedHash): bool
+    {
+        if ($expectedHash === null) {
+            return true;
+        }
+
+        $hash = hash_file('sha256', $filename);
+
+        if ($hash === false) {
+            return false;
+        }
+
+        return hash_equals($hash, $expectedHash);
+    }
 }
diff --git a/src/Vocab/VocabLoader.php b/src/Vocab/VocabLoader.php
index a308fbd..fd4156f 100644
--- a/src/Vocab/VocabLoader.php
+++ b/src/Vocab/VocabLoader.php
@@ -7,5 +7,5 @@
 interface VocabLoader
 {
     /** @param non-empty-string $uri */
-    public function load(string $uri): Vocab;
+    public function load(string $uri, string|null $checksum = null): Vocab;
 }
diff --git a/tests/Vocab/Loader/DefaultVocabLoaderTest.php b/tests/Vocab/Loader/DefaultVocabLoaderTest.php
new file mode 100644
index 0000000..da60faa
--- /dev/null
+++ b/tests/Vocab/Loader/DefaultVocabLoaderTest.php
@@ -0,0 +1,84 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Yethee\Tiktoken\Tests\Vocab\Loader;
+
+use PHPUnit\Framework\TestCase;
+use RecursiveDirectoryIterator;
+use RecursiveIteratorIterator;
+use Yethee\Tiktoken\Vocab\Loader\DefaultVocabLoader;
+
+use function copy;
+use function dirname;
+use function file_put_contents;
+use function hash;
+use function rmdir;
+use function sys_get_temp_dir;
+use function unlink;
+
+final class DefaultVocabLoaderTest extends TestCase
+{
+    private string $cacheDir;
+
+    public function testLoadFromCache(): void
+    {
+        $loader = new DefaultVocabLoader($this->cacheDir);
+
+        $vocabUrl = 'http://localhost/cl100k_base.tiktoken';
+        $cacheFile = $this->cacheDir . '/' . hash('sha1', $vocabUrl);
+
+        copy(dirname(__DIR__, 2) . '/Fixtures/cl100k_base.tiktoken', $cacheFile);
+        self::assertFileEquals(dirname(__DIR__, 2) . '/Fixtures/cl100k_base.tiktoken', $cacheFile);
+
+        $vocab = $loader->load($vocabUrl, '223921b76ee99bde995b7ff738513eef100fb51d18c93597a113bcffe865b2a7');
+
+        self::assertSame(100256, $vocab->count());
+    }
+
+    public function testInvalidateCacheWhenChecksumMismatch(): void
+    {
+        $loader = new DefaultVocabLoader($this->cacheDir);
+
+        $vocabUrl = dirname(__DIR__, 2) . '/Fixtures/p50k_base.tiktoken';
+        $cacheFile = $this->cacheDir . '/' . hash('sha1', $vocabUrl);
+
+        file_put_contents($cacheFile, 'outdated content');
+        self::assertFileExists($cacheFile);
+
+        $vocab = $loader->load($vocabUrl, '94b5ca7dff4d00767bc256fdd1b27e5b17361d7b8a5f968547f9f23eb70d2069');
+
+        self::assertSame(50280, $vocab->count());
+
+        self::assertFileExists($cacheFile);
+        self::assertFileEquals($vocabUrl, $cacheFile);
+    }
+
+    protected function setUp(): void
+    {
+        $this->cacheDir = sys_get_temp_dir() . '/tiktoken-test';
+
+        self::removeDir($this->cacheDir);
+    }
+
+    protected function tearDown(): void
+    {
+        self::removeDir($this->cacheDir);
+    }
+
+    private static function removeDir(string $path): void
+    {
+        $iterator = new RecursiveIteratorIterator(
+            new RecursiveDirectoryIterator($path, RecursiveDirectoryIterator::SKIP_DOTS),
+            RecursiveIteratorIterator::CHILD_FIRST,
+        );
+
+        foreach ($iterator as $entry) {
+            if ($entry->isFile()) {
+                unlink($entry->getPathname());
+            } else {
+                rmdir($entry->getPathname());
+            }
+        }
+    }
+}