diff --git a/module/VuFind/src/VuFind/Bootstrapper.php b/module/VuFind/src/VuFind/Bootstrapper.php
index 5343f254bc5edb832def8490b0cc98101b54db34..baf2aa69a544731d440bf2bc4a4017c138b4b8c4 100644
--- a/module/VuFind/src/VuFind/Bootstrapper.php
+++ b/module/VuFind/src/VuFind/Bootstrapper.php
@@ -342,9 +342,10 @@ class Bootstrapper
             $viewModel = $sm->get('viewmanager')->getViewModel();
             $viewModel->setVariable('userLang', $language);
             $viewModel->setVariable('allLangs', $config->Languages);
-            $rtlLangs = array_map(
-                'trim', explode(',', $config->LanguageSettings->rtl_langs)
-            );
+            $rtlLangs = isset($config->LanguageSettings->rtl_langs)
+                ? array_map(
+                    'trim', explode(',', $config->LanguageSettings->rtl_langs)
+                ) : [];
             $viewModel->setVariable('rtl', in_array($language, $rtlLangs));
         };
         $this->events->attach('dispatch.error', $callback, 10000);
@@ -468,4 +469,4 @@ class Bootstrapper
         };
         $this->events->attach('render.error', $callback, 10000);
     }
-}
\ No newline at end of file
+}