diff --git a/src/main/java/org/example/service/getHistoryServiceImpl.java b/src/main/java/org/example/service/getHistoryServiceImpl.java
index 3ff22bd081a3ec902df3c7cde4e1c1e542b60015..5de7ab9466ba7bec1a2837a1dba748577a090e99 100644
--- a/src/main/java/org/example/service/getHistoryServiceImpl.java
+++ b/src/main/java/org/example/service/getHistoryServiceImpl.java
@@ -77,7 +77,7 @@ public class getHistoryServiceImpl implements getHistoryService {
             while (result.next()) {
                 json += "{\"product_id\": " + result.getInt("product_id") + ", \"quantity\": "
                     + result.getInt("quantity") + ", \"timestamp\": "
-                    + result.getString("timestamp") + ", \"history_id\": \"" + result.getInt("history_id") + "\"},";
+                    + "\"" + result.getString("timestamp") + "\"" + ", \"history_id\": \"" + result.getInt("history_id") + "\"},";
                 found = true;
             }
             json = json.substring(0, json.length() - 1);