diff --git a/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php b/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
index 3088a770e..e928a6e9b 100644
--- a/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
+++ b/lib/Doctrine/ODM/MongoDB/Mapping/ClassMetadata.php
@@ -2408,7 +2408,7 @@ public function mapField(array $mapping): array
                 } elseif (empty($mapping['type'])) {
                     $mapping['type'] = $this->generatorType === self::GENERATOR_TYPE_INCREMENT ? Type::INT : Type::CUSTOMID;
                 }
-            } elseif ($mapping['type'] !== Type::UUID) {
+            } elseif (empty($mapping['type']) || $mapping['type'] !== Type::UUID) {
                 $mapping['type'] = Type::ID;
             }