diff --git a/bin/bootstrap.php b/bin/bootstrap.php
index 832de8d11ca..ebf29e2ca0b 100644
--- a/bin/bootstrap.php
+++ b/bin/bootstrap.php
@@ -1,6 +1,8 @@
 <?php declare(strict_types=1);
 
-$projectAutoload = getcwd() . '/vendor/autoload.php';
+$cwd = getcwd();
+
+$projectAutoload = $cwd . '/vendor/autoload.php';
 if (is_file($projectAutoload)) {
     require $projectAutoload;
 }
@@ -23,7 +25,29 @@ foreach ($possibleAutoloadPaths as $possibleAutoloadPath) {
     }
 }
 
-die(sprintf(
+$composer_json_path = $cwd . '/composer.json';
+if (file_exists($composer_json_path)) {
+    $contents = file_get_contents($composer_json_path);
+
+    $composer_settings = json_decode($contents, true);
+    if (!is_array($composer_settings)) {
+        fwrite(STDERR, "Failed to load '$composer_json_path'\n");
+        return 1;
+    }
+
+    $vendor_path = $composer_settings['config']['vendor-dir'] ?? $cwd . '/vendor';
+    if (!is_dir($vendor_path)) {
+        fwrite(STDERR, "Please check if 'composer.phar install' was run already (expected to find '$vendor_path')\n");
+        return 1;
+    }
+
+    /** @noinspection PhpIncludeInspection */
+    require $vendor_path . '/autoload.php';
+    return;
+}
+
+fwrite(STDERR, sprintf(
     'Composer autoload.php was not found in paths "%s". Have you ran "composer update"?',
     implode('", "', $possibleAutoloadPaths)
 ));
+exit(1);