diff --git a/scm-webapp/src/main/java/sonia/scm/api/v2/resources/BaseMapper.java b/scm-webapp/src/main/java/sonia/scm/api/v2/resources/BaseMapper.java
new file mode 100644
index 0000000000..6aea500c78
--- /dev/null
+++ b/scm-webapp/src/main/java/sonia/scm/api/v2/resources/BaseMapper.java
@@ -0,0 +1,20 @@
+package sonia.scm.api.v2.resources;
+
+import sonia.scm.util.AssertUtil;
+
+import java.time.Instant;
+import java.util.Optional;
+
+class BaseMapper {
+
+  Instant mapTime(Long epochMilli) {
+    AssertUtil.assertIsNotNull(epochMilli);
+    return Instant.ofEpochMilli(epochMilli);
+  }
+
+  Optional<Instant> mapOptionalTime(Long epochMilli) {
+    return Optional
+      .ofNullable(epochMilli)
+      .map(Instant::ofEpochMilli);
+  }
+}
diff --git a/scm-webapp/src/main/java/sonia/scm/api/v2/resources/GroupToGroupDtoMapper.java b/scm-webapp/src/main/java/sonia/scm/api/v2/resources/GroupToGroupDtoMapper.java
index c28f937993..0472b8dcf5 100644
--- a/scm-webapp/src/main/java/sonia/scm/api/v2/resources/GroupToGroupDtoMapper.java
+++ b/scm-webapp/src/main/java/sonia/scm/api/v2/resources/GroupToGroupDtoMapper.java
@@ -4,23 +4,19 @@ import de.otto.edison.hal.Links;
 import org.mapstruct.AfterMapping;
 import org.mapstruct.Context;
 import org.mapstruct.Mapper;
-import org.mapstruct.Mapping;
 import org.mapstruct.MappingTarget;
 import sonia.scm.group.Group;
 import sonia.scm.group.GroupPermissions;
-import sonia.scm.util.AssertUtil;
 
 import javax.ws.rs.core.UriInfo;
-import java.time.Instant;
 import java.util.List;
-import java.util.Optional;
 import java.util.stream.Collectors;
 
 import static de.otto.edison.hal.Link.link;
 import static de.otto.edison.hal.Links.linkingTo;
 
 @Mapper
-public abstract class GroupToGroupDtoMapper {
+public abstract class GroupToGroupDtoMapper extends BaseMapper {
 
   public abstract GroupDto map(Group group, @Context UriInfo uriInfo);
 
@@ -55,17 +51,4 @@ public abstract class GroupToGroupDtoMapper {
     memberDto.add(linksBuilder.build());
     return memberDto;
   }
-
-  @Mapping(target = "creationDate")
-  Instant mapTime(Long epochMilli) {
-    AssertUtil.assertIsNotNull(epochMilli);
-    return Instant.ofEpochMilli(epochMilli);
-  }
-
-  @Mapping(target = "lastModified")
-  Optional<Instant> mapOptionalTime(Long epochMilli) {
-    return Optional
-      .ofNullable(epochMilli)
-      .map(Instant::ofEpochMilli);
-  }
 }
diff --git a/scm-webapp/src/main/java/sonia/scm/api/v2/resources/UserToUserDtoMapper.java b/scm-webapp/src/main/java/sonia/scm/api/v2/resources/UserToUserDtoMapper.java
index b0f9b41ea9..7a416bc675 100644
--- a/scm-webapp/src/main/java/sonia/scm/api/v2/resources/UserToUserDtoMapper.java
+++ b/scm-webapp/src/main/java/sonia/scm/api/v2/resources/UserToUserDtoMapper.java
@@ -8,17 +8,14 @@ import org.mapstruct.MappingTarget;
 import sonia.scm.api.rest.resources.UserResource;
 import sonia.scm.user.User;
 import sonia.scm.user.UserPermissions;
-import sonia.scm.util.AssertUtil;
 
 import javax.ws.rs.core.UriInfo;
-import java.time.Instant;
-import java.util.Optional;
 
 import static de.otto.edison.hal.Link.link;
 import static de.otto.edison.hal.Links.linkingTo;
 
 @Mapper
-public abstract class UserToUserDtoMapper {
+public abstract class UserToUserDtoMapper extends BaseMapper {
 
   public abstract UserDto map(User user, @Context UriInfo uriInfo);
 
@@ -44,15 +41,4 @@ public abstract class UserToUserDtoMapper {
     target.add(
       linksBuilder.build());
   }
-
-  Instant mapTime(Long epochMilli) {
-    AssertUtil.assertIsNotNull(epochMilli);
-    return Instant.ofEpochMilli(epochMilli);
-  }
-
-  Optional<Instant> mapOptionalTime(Long epochMilli) {
-    return Optional
-      .ofNullable(epochMilli)
-      .map(Instant::ofEpochMilli);
-  }
 }