diff --git a/src/Event/Http/FpmHandler.php b/src/Event/Http/FpmHandler.php
index <HASH>..<HASH> 100644
--- a/src/Event/Http/FpmHandler.php
+++ b/src/Event/Http/FpmHandler.php
@@ -32,6 +32,11 @@ final class FpmHandler extends HttpHandler
     private const SOCKET = '/tmp/.bref/php-fpm.sock';
     private const PID_FILE = '/tmp/.bref/php-fpm.pid';
     private const CONFIG = '/opt/bref/etc/php-fpm.conf';
+    /**
+     * We define this constant instead of using the PHP one because that avoids
+     * depending on the pcntl extension.
+     */
+    private const SIGTERM = 15;
 
     /** @var Client|null */
     private $client;
@@ -243,7 +248,7 @@ final class FpmHandler extends HttpHandler
         echo "PHP-FPM seems to be running already. This might be because Lambda stopped the bootstrap process but didn't leave us an opportunity to stop PHP-FPM (did Lambda timeout?). Stopping PHP-FPM now to restart from a blank slate.\n";
 
         // The previous PHP-FPM process is running, let's try to kill it properly
-        $result = posix_kill($pid, SIGTERM);
+        $result = posix_kill($pid, self::SIGTERM);
         if ($result === false) {
             echo "PHP-FPM's PID file contained a PID that doesn't exist, assuming PHP-FPM isn't running.\n";
             unlink(self::SOCKET);
Remove a dependency to the pcntl extension