diff --git a/user-manager-server/src/main/java/de/itvsh/kop/user/UserService.java b/user-manager-server/src/main/java/de/itvsh/kop/user/UserService.java
index 1cc57966d5c47d23923e5a6a8d72539826393fe2..7c83d831c799ad9ab738afbf97bd12dc24941bf2 100644
--- a/user-manager-server/src/main/java/de/itvsh/kop/user/UserService.java
+++ b/user-manager-server/src/main/java/de/itvsh/kop/user/UserService.java
@@ -11,6 +11,7 @@ import de.itvsh.kop.user.common.errorhandling.ResourceNotFoundException;
 
 @ApplicationScoped
 public class UserService {
+	static final String UUID_PATTERN = "-";
 
 	@Inject
 	UserRepository repository;
@@ -45,7 +46,7 @@ public class UserService {
 	}
 
 	public User findById(String id) {
-		if (id.contains("-")) {
+		if (id.contains(UUID_PATTERN)) {
 			// TODO wenn user migriert wurden wieder entfernen.
 			return repository.findByExternalId(id).orElseThrow(() -> new ResourceNotFoundException(User.class, id));
 		}
diff --git a/user-manager-server/src/test/java/de/itvsh/kop/user/UserServiceTest.java b/user-manager-server/src/test/java/de/itvsh/kop/user/UserServiceTest.java
index 9b683fdc465604b217e3d5bd3023461cc1af870d..79d93d23f090f4bd5055a56344345dc7b67b22e9 100644
--- a/user-manager-server/src/test/java/de/itvsh/kop/user/UserServiceTest.java
+++ b/user-manager-server/src/test/java/de/itvsh/kop/user/UserServiceTest.java
@@ -5,6 +5,7 @@ import static org.mockito.Mockito.*;
 
 import java.time.Instant;
 import java.util.Optional;
+import java.util.UUID;
 
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Nested;
@@ -23,6 +24,28 @@ class UserServiceTest {
 	@Mock
 	KeycloakUserRemoteService keycloakRemoteService;
 
+	@DisplayName("Find")
+	@Nested
+	class TestFind {
+		@Test
+		void shouldCallFindById() {
+			when(repository.findById(anyString())).thenReturn(Optional.of(UserTestFactory.create()));
+
+			service.findById("xxx");
+
+			verify(repository).findById(anyString());
+		}
+
+		@Test
+		void shouldCallFindByExternalId() {
+			when(repository.findByExternalId(any())).thenReturn(Optional.of(UserTestFactory.create()));
+
+			service.findById(UUID.randomUUID().toString());
+
+			verify(repository).findByExternalId(anyString());
+		}
+	}
+
 	@DisplayName("Save")
 	@Nested
 	class TestSave {