diff --git a/src/main/java/com/sellbycar/marketplace/ad/AdvertisementServiceImpl.java b/src/main/java/com/sellbycar/marketplace/ad/AdvertisementServiceImpl.java
index cabefbc..d96cbf0 100644
--- a/src/main/java/com/sellbycar/marketplace/ad/AdvertisementServiceImpl.java
+++ b/src/main/java/com/sellbycar/marketplace/ad/AdvertisementServiceImpl.java
@@ -5,6 +5,7 @@
 import com.sellbycar.marketplace.image.ImageDAO;
 import com.sellbycar.marketplace.image.ImageService;
 import com.sellbycar.marketplace.user.UserDAO;
+import com.sellbycar.marketplace.user.UserRepository;
 import com.sellbycar.marketplace.user.UserService;
 import com.sellbycar.marketplace.util.exception.RequestException;
 import jakarta.transaction.Transactional;
@@ -32,6 +33,7 @@ public class AdvertisementServiceImpl implements AdvertisementService {
     private final UserService userService;
     private final AdvertisementMapper advertisementMapper;
     private final ImageService imageService;
+    private final UserRepository userRepository;
 
     @Override
     public List<AdvertisementDTO> findAdvertisements(AdvertisementFilter filter, Sort sort, int page, int size) {
@@ -114,7 +116,8 @@ public AdvertisementDAO addToFavoriteList(Long id) {
         UserDAO user = userService.getUserFromSecurityContextHolder();
         AdvertisementDAO advertisement = advertisementRepository.findById(id)
                 .orElseThrow(() -> RequestException.notFound("Advertisement does not exist."));
-        user.getFavorites().add(advertisement);
+        user.addFavorite(advertisement);
+        userRepository.save(user);
         return advertisement;
     }
 
@@ -123,7 +126,8 @@ public void removeFromFavoriteList(Long id) {
         UserDAO user = userService.getUserFromSecurityContextHolder();
         AdvertisementDAO advertisement = advertisementRepository.findById(id)
                 .orElseThrow(() -> RequestException.notFound("Advertisement does not exist."));
-        user.getFavorites().remove(advertisement);
+        user.removeFavorite(advertisement);
+        userRepository.save(user);
     }
 
     @Transactional
diff --git a/src/main/java/com/sellbycar/marketplace/user/UserDAO.java b/src/main/java/com/sellbycar/marketplace/user/UserDAO.java
index f58b2af..f0bb1c0 100644
--- a/src/main/java/com/sellbycar/marketplace/user/UserDAO.java
+++ b/src/main/java/com/sellbycar/marketplace/user/UserDAO.java
@@ -71,4 +71,18 @@ public class UserDAO implements Serializable {
 
     @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
     private Set<AdvertisementDAO> advertisements;
+
+    public void addFavorite(AdvertisementDAO advertisement) {
+        if (favorites == null) {
+            favorites = Set.of(advertisement);
+        } else {
+            favorites.add(advertisement);
+        }
+    }
+
+    public void removeFavorite(AdvertisementDAO advertisement) {
+        if (favorites != null) {
+            favorites.remove(advertisement);
+        }
+    }
 }