diff --git a/data/model/repository.py b/data/model/repository.py
index a1b8196e1..24d82e697 100644
--- a/data/model/repository.py
+++ b/data/model/repository.py
@@ -163,11 +163,10 @@ def garbage_collect_repo(repo, extra_candidate_set=None):
                            .where(RepositoryTag.repository == repo.id,
                                   Candidate.id << candidates_orphans))
 
-    direct_referenced = (Candidate
-                         .select(Candidate.id)
-                         .join(RepositoryTag)
+    direct_referenced = (RepositoryTag
+                         .select(RepositoryTag.image)
                          .where(RepositoryTag.repository == repo.id,
-                                Candidate.id << candidates_orphans))
+                                RepositoryTag.image << candidates_orphans))
 
     referenced_candidates = (direct_referenced | ancestor_referenced)