@@ -5,13 +5,15 @@
 use PHPStan\Command\Output;
 use PHPStan\DependencyInjection\AutowiredService;
 use PHPStan\Diagnose\DiagnoseExtension;
+use PHPStan\Php\PhpVersion;
 use function php_uname;
 use function phpversion;
 use function sprintf;
 use const PHP_DEBUG;
 use const PHP_MAJOR_VERSION;
 use const PHP_MINOR_VERSION;
 use const PHP_OS_FAMILY;
+use const PHP_VERSION_ID;
 use const PHP_ZTS;
 
 #[AutowiredService]
@@ -48,8 +50,15 @@ public function print(Output $output): void
 			} else {
 				$workerBinaryLine = 'loaded via php.ini, workers inherit it';
 			}
+		} elseif ($workerBinary !== null) {
+			$workerBinaryLine = $workerBinary;
+		} elseif (PHP_VERSION_ID < TurboExtensionSelector::MINIMUM_PHP_VERSION_ID) {
+			$workerBinaryLine = sprintf(
+				'none built for PHP < %s',
+				(new PhpVersion(TurboExtensionSelector::MINIMUM_PHP_VERSION_ID))->getVersionString(),
+			);
 		} else {
-			$workerBinaryLine = $workerBinary ?? 'none found';
+			$workerBinaryLine = 'none found';
 		}
 		$output->writeLineFormatted(sprintf(
 			'<info>Turbo worker binary:</info> %s',
 
@@ -13,6 +13,7 @@
 use const PHP_MAJOR_VERSION;
 use const PHP_MINOR_VERSION;
 use const PHP_OS_FAMILY;
+use const PHP_VERSION_ID;
 use const PHP_ZTS;
 
 /**
@@ -26,7 +27,8 @@
  * Windows) by the phar.yml commit job, so they only exist for phar-based
  * installations —
  * a source checkout loads its locally built extension through php.ini
- * instead. Only non-debug builds are shipped; ZTS variants (-zts filename
+ * instead. Only non-debug builds for PHP >= MINIMUM_PHP_VERSION_ID are
+ * shipped; ZTS variants (-zts filename
  * suffix) exist for linux-gnu and Windows so hosts with a thread-safe PHP
  * (like PMMP's bundled build) are covered too. Workers run the regular
  * entrypoint, so TurboExtensionEnabler still gates activation on the
@@ -39,6 +41,13 @@
 final class TurboExtensionSelector
 {
 
+	/**
+	 * The oldest PHP the extension is built for — the phar.yml turbo-compile
+	 * matrix. Older runtimes have no binary to find, so they skip the lookup
+	 * (and with it the process restart) entirely.
+	 */
+	public const MINIMUM_PHP_VERSION_ID = 80300;
+
 	public static function findExtensionForWorkers(): ?string
 	{
 		if (TurboExtensionEnabler::isLoaded()) {
@@ -63,6 +72,9 @@ public static function findExtensionForWorkers(): ?string
 	 */
 	public static function findExtension(): ?string
 	{
+		if (PHP_VERSION_ID < self::MINIMUM_PHP_VERSION_ID) {
+			return null;
+		}
 		if ((bool) PHP_DEBUG) {
 			return null;
 		}