diff --git a/src/Psalm/Config.php b/src/Psalm/Config.php
index 9c0b4a2dac4..36b74793018 100644
--- a/src/Psalm/Config.php
+++ b/src/Psalm/Config.php
@@ -836,7 +836,7 @@ private static function fromXmlAndPaths(string $base_dir, string $file_contents,
 
             $config->level = $attribute_text;
         } elseif (isset($config_xml['totallyTyped'])) {
-            $totally_typed = $config_xml['totallyTyped'];
+            $totally_typed = (string) $config_xml['totallyTyped'];
 
             if ($totally_typed === 'true' || $totally_typed === '1') {
                 $config->level = 1;