diff --git a/src/Illuminate/Database/Eloquent/Concerns/GuardsAttributes.php b/src/Illuminate/Database/Eloquent/Concerns/GuardsAttributes.php
index 491a6caaf88b..bfb67754beff 100644
--- a/src/Illuminate/Database/Eloquent/Concerns/GuardsAttributes.php
+++ b/src/Illuminate/Database/Eloquent/Concerns/GuardsAttributes.php
@@ -202,7 +202,7 @@ public function isGuarded($key)
         }
 
         return $this->getGuarded() == ['*'] ||
-               ! empty(preg_grep('/^'.preg_quote($key).'$/i', $this->getGuarded())) ||
+               ! empty(preg_grep('/^'.preg_quote($key, '/').'$/i', $this->getGuarded())) ||
                ! $this->isGuardableColumn($key);
     }