diff --git a/src/main/resources/db/changelog/7-hs-hosting/701-hosting-asset/7010-hs-hosting-asset.sql b/src/main/resources/db/changelog/7-hs-hosting/701-hosting-asset/7010-hs-hosting-asset.sql
index 304e7337..d8d1393e 100644
--- a/src/main/resources/db/changelog/7-hs-hosting/701-hosting-asset/7010-hs-hosting-asset.sql
+++ b/src/main/resources/db/changelog/7-hs-hosting/701-hosting-asset/7010-hs-hosting-asset.sql
@@ -41,6 +41,8 @@ create table if not exists hs_hosting.asset
     config              jsonb not null,
     alarmContactUuid    uuid null references hs_office.contact(uuid) initially deferred,
 
+    unique (type, identifier), -- at least as long as we need to be compatible to the legacy system
+
     constraint hosting_asset_has_booking_item_or_parent_asset
         check (bookingItemUuid is not null or parentAssetUuid is not null or type in ('DOMAIN_SETUP', 'IPV4_NUMBER', 'IPV6_NUMBER'))
 );
diff --git a/src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/HsHostingAssetRepositoryIntegrationTest.java b/src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/HsHostingAssetRepositoryIntegrationTest.java
index e04591c7..90ac5bf6 100644
--- a/src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/HsHostingAssetRepositoryIntegrationTest.java
+++ b/src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/HsHostingAssetRepositoryIntegrationTest.java
@@ -10,6 +10,7 @@ import net.hostsharing.hsadminng.rbac.role.RawRbacRoleRepository;
 import net.hostsharing.hsadminng.mapper.Array;
 import net.hostsharing.hsadminng.rbac.test.ContextBasedTestWithCleanup;
 import net.hostsharing.hsadminng.rbac.test.JpaAttempt;
+import org.hibernate.exception.ConstraintViolationException;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -163,6 +164,31 @@ class HsHostingAssetRepositoryIntegrationTest extends ContextBasedTestWithCleanu
             assertThat(realAssetRepo.count()).isEqualTo(count + 1);
         }
 
+        @Test
+        public void identifiersForTheSameTypeAreUnique() {
+            // given
+            context("superuser-alex@hostsharing.net"); // TODO.test: remove context(...) once all entities have real entities
+            final var count = realAssetRepo.count();
+            final var givenManagedServer = givenHostingAsset("D-1000111 default project", MANAGED_SERVER);
+            final var newWebspaceBookingItem = newBookingItem(givenManagedServer.getBookingItem(), HsBookingItemType.MANAGED_WEBSPACE, "fir01");
+
+            // when
+            final var result = attempt(em, () -> {
+                final var newAsset = HsHostingAssetRbacEntity.builder()
+                        .bookingItem(newWebspaceBookingItem)
+                        .parentAsset(givenManagedServer)
+                        .caption("some managed webspace with existing identifier")
+                        .type(MANAGED_WEBSPACE)
+                        .identifier("fir01")
+                        .build();
+                return toCleanup(rbacAssetRepo.save(newAsset));
+            });
+
+            // then
+            result.assertExceptionWithRootCauseMessage(ConstraintViolationException.class,
+                    "duplicate key value violates unique constraint \"asset_type_identifier_key\"");
+        }
+
         @Test
         public void createsAndGrantsRoles() {
             // given