diff --git a/README.md b/README.md
index 138962f2ec2..6fa39b95041 100644
--- a/README.md
+++ b/README.md
@@ -255,6 +255,12 @@ Learn more in
 
 ## How-to
 
+### How to fix "Access denied."
+
+Output is from php-fpm. It is unable to read index.php.
+
+    chown rss-bridge:rss-bridge /var/www/rss-bridge/index.php
+
 ### How to password-protect the instance (token)
 
 Modify `config.ini.php`:
diff --git a/index.php b/index.php
index 56a94ac61fe..7144ae27528 100644
--- a/index.php
+++ b/index.php
@@ -6,6 +6,12 @@
     exit;
 }
 
+if (! is_readable(__DIR__ . '/lib/bootstrap.php')) {
+    http_response_code(500);
+    print 'Unable to read lib/bootstrap.php. Check file permissions.';
+    exit;
+}
+
 require_once __DIR__ . '/lib/bootstrap.php';
 
 set_exception_handler(function (\Throwable $e) {