diff --git a/Index/MappingBuilder.php b/Index/MappingBuilder.php
index 21ae871..9782e84 100644
--- a/Index/MappingBuilder.php
+++ b/Index/MappingBuilder.php
@@ -107,6 +107,9 @@ class MappingBuilder
             if (!isset($property['type'])) {
                 $property['type'] = 'string';
             }
+            if ($property['type'] == 'multi_field' && isset($property['fields'])) {
+                $this->fixProperties($property['fields']);
+            }
             if (isset($property['properties'])) {
                 $this->fixProperties($property['properties']);
             }