diff --git a/src/Illuminate/Support/Str.php b/src/Illuminate/Support/Str.php
index b970d421d0f2..cbabea9fc9db 100644
--- a/src/Illuminate/Support/Str.php
+++ b/src/Illuminate/Support/Str.php
@@ -542,7 +542,7 @@ public static function isUuid($value)
             return false;
         }
 
-        return preg_match('/^[\da-f]{8}-[\da-f]{4}-[\da-f]{4}-[\da-f]{4}-[\da-f]{12}$/iD', $value) > 0;
+        return preg_match('/^[\da-fA-F]{8}-[\da-fA-F]{4}-[\da-fA-F]{4}-[\da-fA-F]{4}-[\da-fA-F]{12}$/D', $value) > 0;
     }
 
     /**