diff --git a/frontend/app/components/api/api-v3/hal-resources/work-package-resource.service.ts b/frontend/app/components/api/api-v3/hal-resources/work-package-resource.service.ts
index 4c99af027d..2127c442cc 100644
--- a/frontend/app/components/api/api-v3/hal-resources/work-package-resource.service.ts
+++ b/frontend/app/components/api/api-v3/hal-resources/work-package-resource.service.ts
@@ -58,7 +58,7 @@ interface WorkPackageResourceLinks extends WorkPackageResourceEmbedded {
   addAttachment(attachment:HalResource):ng.IPromise<any>;
   addChild(child:HalResource):ng.IPromise<any>;
   addComment(comment:HalResource):ng.IPromise<any>;
-  addRelation(relation:HalResource):ng.IPromise<any>;
+  addRelation(relation:any):ng.IPromise<any>;
   addWatcher(watcher:HalResource):ng.IPromise<any>;
   changeParent(newParent:WorkPackageResource):ng.IPromise<any>;
   copy():ng.IPromise<WorkPackageResource>;