diff --git a/src/Commands/core/DrupalCommands.php b/src/Commands/core/DrupalCommands.php
index b0ce6d1bd8..6e33e2c3ea 100644
--- a/src/Commands/core/DrupalCommands.php
+++ b/src/Commands/core/DrupalCommands.php
@@ -95,7 +95,7 @@ public function requirements($options = ['format' => 'table', 'severity' => -1,
         foreach ($requirements as $key => $info) {
             if (is_numeric($key)) {
                 unset($requirements[$key]);
-                $new_key = strtolower(str_replace(' ', '_', $info['title']));
+                $new_key = strtolower(str_replace(' ', '_', (string) $info['title']));
                 $requirements[$new_key] = $info;
             }
         }