diff --git a/package.php b/package.php
old mode 100644
new mode 100755
diff --git a/phpunit/src/Build/PrecompiledHeaderManagerTest.php b/phpunit/src/Build/PrecompiledHeaderManagerTest.php
new file mode 100644
index 00000000..72df23b3
--- /dev/null
+++ b/phpunit/src/Build/PrecompiledHeaderManagerTest.php
@@ -0,0 +1,88 @@
+<?php
+
+namespace TypePhp\Tests\Build;
+
+use PHPUnit\Framework\TestCase;
+use TypePhp\Backend\CompilerBackend;
+use TypePhp\Build\CompileOptions;
+use TypePhp\Build\NativeBuilder;
+use TypePhp\Build\PrecompiledHeaderManager;
+
+final class PrecompiledHeaderManagerTest extends TestCase
+{
+    private string $cacheDirectory;
+
+    protected function setUp(): void
+    {
+        $this->cacheDirectory = sys_get_temp_dir() . '/typephp_pch_' . bin2hex(random_bytes(8));
+        mkdir($this->cacheDirectory, 0777, true);
+    }
+
+    protected function tearDown(): void
+    {
+        $this->removeDirectory($this->cacheDirectory);
+    }
+
+    public function testPreparePrunesExpiredAndExcessCacheEntries(): void
+    {
+        $oldDirectory = $this->createCacheEntry(1, time() - 31 * 86400);
+        for ($i = 2; $i <= 10; $i++) {
+            $this->createCacheEntry($i, time() - (10 - $i));
+        }
+        $unmanagedDirectory = $this->cacheDirectory . '/keep-me';
+        mkdir($unmanagedDirectory);
+
+        $backend = $this->createMock(CompilerBackend::class);
+        $backend->method('supportsPrecompiledHeaders')->willReturn(true);
+        $backend->method('getName')->willReturn('test');
+        $backend->method('getCompilerCommand')->willReturn('true');
+        $backend->method('getPrecompiledHeaderArtifact')
+            ->willReturnCallback(static fn(string $header): string => $header . '.gch');
+        $backend->method('buildNativeCompileCommand')
+            ->willReturnCallback(
+                static fn(string $source, string $object): string => 'touch ' . escapeshellarg($object),
+            );
+
+        $result = (new PrecompiledHeaderManager($backend, new NativeBuilder($backend)))->prepare(
+            ['cstring', 'phpx.h'],
+            [],
+            $this->cacheDirectory,
+            new CompileOptions([]),
+        );
+
+        $this->assertFileExists($result['artifact']);
+        $this->assertStringContainsString("#include <cstring>\n#include <phpx.h>\n", file_get_contents($result['header']));
+        $this->assertDirectoryDoesNotExist($oldDirectory);
+        $this->assertDirectoryExists($unmanagedDirectory);
+
+        $managedEntries = array_filter(
+            scandir($this->cacheDirectory),
+            static fn(string $entry): bool => preg_match('/^[a-f0-9]{24}$/D', $entry) === 1,
+        );
+        $this->assertCount(8, $managedEntries);
+    }
+
+    private function createCacheEntry(int $number, int $mtime): string
+    {
+        $directory = $this->cacheDirectory . '/' . sprintf('%024x', $number);
+        mkdir($directory);
+        file_put_contents($directory . '/typephp_pch.hpp.gch', 'cached');
+        touch($directory, $mtime);
+        return $directory;
+    }
+
+    private function removeDirectory(string $directory): void
+    {
+        if (!is_dir($directory)) {
+            return;
+        }
+        $iterator = new \RecursiveIteratorIterator(
+            new \RecursiveDirectoryIterator($directory, \FilesystemIterator::SKIP_DOTS),
+            \RecursiveIteratorIterator::CHILD_FIRST,
+        );
+        foreach ($iterator as $entry) {
+            $entry->isDir() ? rmdir($entry->getPathname()) : unlink($entry->getPathname());
+        }
+        rmdir($directory);
+    }
+}
diff --git a/src/Build/PrecompiledHeaderManager.php b/src/Build/PrecompiledHeaderManager.php
index 53d00f04..21549ac6 100644
--- a/src/Build/PrecompiledHeaderManager.php
+++ b/src/Build/PrecompiledHeaderManager.php
@@ -6,6 +6,9 @@ use TypePhp\Backend\CompilerBackend;
 
 final readonly class PrecompiledHeaderManager
 {
+    private const int MAX_CACHE_ENTRIES = 8;
+    private const int MAX_CACHE_AGE = 30 * 86400;
+
     public function __construct(
         private CompilerBackend $backend,
         private NativeBuilder $builder,
@@ -46,6 +49,7 @@ final readonly class PrecompiledHeaderManager
         }
 
         if (is_file($artifact)) {
+            $this->markUsedAndPrune($cacheDirectory, $directory);
             return ['header' => $headerFile, 'artifact' => $artifact, 'cached' => true, 'command' => ''];
         }
 
@@ -55,9 +59,62 @@ final readonly class PrecompiledHeaderManager
             throw new \RuntimeException('Failed to build PHPX precompiled header' . ($message === '' ? '' : ': ' . $message));
         }
 
+        $this->markUsedAndPrune($cacheDirectory, $directory);
         return ['header' => $headerFile, 'artifact' => $artifact, 'cached' => false, 'command' => $result['command']];
     }
 
+    private function markUsedAndPrune(string $cacheDirectory, string $currentDirectory): void
+    {
+        // Cache cleanup is best-effort and must never disable an otherwise
+        // usable PCH merely because an old entry cannot be removed.
+        @touch($currentDirectory);
+
+        try {
+            $entries = $this->getCacheEntries($cacheDirectory, $currentDirectory);
+            $cutoff = time() - self::MAX_CACHE_AGE;
+            foreach ($entries as $index => $entry) {
+                if ($entry['mtime'] < $cutoff || $index >= self::MAX_CACHE_ENTRIES - 1) {
+                    $this->removeCacheDirectory($entry['path']);
+                }
+            }
+        } catch (\Throwable) {
+            // Ignore cleanup errors; the active artifact is already valid.
+        }
+    }
+
+    /** @return list<array{path: string, mtime: int}> */
+    private function getCacheEntries(string $cacheDirectory, string $currentDirectory): array
+    {
+        $entries = [];
+        $iterator = new \FilesystemIterator($cacheDirectory, \FilesystemIterator::SKIP_DOTS);
+        foreach ($iterator as $entry) {
+            $path = $entry->getPathname();
+            if (!$entry->isDir() || $entry->isLink() || $path === $currentDirectory
+                || preg_match('/^[a-f0-9]{24}$/D', $entry->getFilename()) !== 1) {
+                continue;
+            }
+            $entries[] = ['path' => $path, 'mtime' => $entry->getMTime()];
+        }
+        usort($entries, static fn(array $a, array $b): int => $b['mtime'] <=> $a['mtime']);
+        return $entries;
+    }
+
+    private function removeCacheDirectory(string $directory): void
+    {
+        $iterator = new \RecursiveIteratorIterator(
+            new \RecursiveDirectoryIterator($directory, \FilesystemIterator::SKIP_DOTS),
+            \RecursiveIteratorIterator::CHILD_FIRST,
+        );
+        foreach ($iterator as $entry) {
+            if ($entry->isDir() && !$entry->isLink()) {
+                @rmdir($entry->getPathname());
+            } else {
+                @unlink($entry->getPathname());
+            }
+        }
+        @rmdir($directory);
+    }
+
     /** @param list<string> $headers @param list<string> $dependencyDirectories */
     private function buildFingerprint(array $headers, array $dependencyDirectories, CompileOptions $options): string
     {
diff --git a/src/Translator.php b/src/Translator.php
index 861279a9..52b80885 100644
--- a/src/Translator.php
+++ b/src/Translator.php
@@ -77,6 +77,7 @@ class Translator extends Preprocessor
     protected array $resourceConfig = [];
     protected bool $useRegisterSymbolsFn = false;
     protected array $globalHeaders = [
+        'cstring',
         'phpx.h',
         'phpx_helper.h',
         'phpx_big_int.h',
@@ -746,8 +747,7 @@ class Translator extends Preprocessor
         $this->genClassCeList();
         $this->indentLevel++;
 
-        $code = '#include <cstring>' . PHP_EOL;
-        $code .= $this->genIncludeHeaderFiles();
+        $code = $this->genIncludeHeaderFiles();
 
         if ($this->isBuildModeLib() && !$this->isWindows()) {
             // PHPX's embedded runtime references this CLI-only symbol even when main() is disabled.
diff --git a/version.txt b/version.txt
index 8b37c8cf..dfc8356d 100644
--- a/version.txt
+++ b/version.txt
@@ -1 +1 @@
-1097
\ No newline at end of file
+1098
\ No newline at end of file