diff --git a/CHANGELOG.md b/CHANGELOG.md
index dbee7cfb9..6bcaac83f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,3 +3,4 @@
   - Add the number of hits in search result (#541)
   - Add support for aligned crop in search result (#543)
   - Sanitize the content displayed in the web interface (#539)
+  - Add support of nested null and boolean values (#571 and #568)
diff --git a/meilisearch-core/src/serde/convert_to_string.rs b/meilisearch-core/src/serde/convert_to_string.rs
index bac0de99e..ca5c59a78 100644
--- a/meilisearch-core/src/serde/convert_to_string.rs
+++ b/meilisearch-core/src/serde/convert_to_string.rs
@@ -88,7 +88,7 @@ impl ser::Serializer for ConvertToString {
     }
 
     fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {
-        Err(SerializerError::UnserializableType { type_name: "()" })
+        Ok(String::new())
     }
 
     fn serialize_unit_struct(self, _name: &'static str) -> Result<Self::Ok, Self::Error> {
diff --git a/meilisearch-http/tests/documents_add.rs b/meilisearch-http/tests/documents_add.rs
index ca87a8027..847179c7d 100644
--- a/meilisearch-http/tests/documents_add.rs
+++ b/meilisearch-http/tests/documents_add.rs
@@ -76,3 +76,38 @@ fn check_add_documents_with_nested_boolean() {
     assert_eq!(status_code, 200);
     assert_eq!(response["status"], "processed");
 }
+
+// Test issue https://github.com/meilisearch/MeiliSearch/issues/571
+#[test]
+fn check_add_documents_with_nested_null() {
+    let mut server = common::Server::with_uid("tasks");
+
+    // 1 - Create the index with no primary_key
+
+    let body = json!({ "uid": "tasks" });
+    let (response, status_code) = server.create_index(body);
+    assert_eq!(status_code, 201);
+    assert_eq!(response["primaryKey"], json!(null));
+
+    // 2 - Add a document that contains a null in a nested object
+
+    let body = json!([{ 
+        "id": 0, 
+        "foo": { 
+            "bar": null
+        } 
+    }]);
+
+    let url = "/indexes/tasks/documents";
+    let (response, status_code) = server.post_request(&url, body);
+    eprintln!("{:#?}", response);
+    assert_eq!(status_code, 202);
+    let update_id = response["updateId"].as_u64().unwrap();
+    server.wait_update_id(update_id);
+
+    // 3 - Check update sucess
+
+    let (response, status_code) = server.get_update_status(update_id);
+    assert_eq!(status_code, 200);
+    assert_eq!(response["status"], "processed");
+}