diff --git a/data/model/repository.py b/data/model/repository.py
index 6602bc081..2cd2b6976 100644
--- a/data/model/repository.py
+++ b/data/model/repository.py
@@ -185,11 +185,19 @@ def garbage_collect_repo(repo, extra_candidate_set=None):
   all_storage_id_whitelist = set()
   all_unreferenced_candidates = set()
 
+  # Remove any images directly referenced by tags, to prune the working set.
+  direct_referenced = (RepositoryTag
+                       .select(RepositoryTag.image)
+                       .where(RepositoryTag.repository == repo.id,
+                              RepositoryTag.image << list(candidate_orphan_image_set)))
+  candidate_orphan_image_set.difference_update([t.image_id for t in direct_referenced])
+
   # Iteratively try to remove images from the database. The only images we can remove are those
   # that are not referenced by tags AND not the parents of other images. We continue removing images
   # until no changes are found.
   iteration = 0
-  while candidate_orphan_image_set:
+  making_progress = True
+  while candidate_orphan_image_set and making_progress:
     iteration = iteration + 1
     logger.debug('Starting iteration #%s for GC of repository %s with candidates: %s', iteration,
                  repo.id, candidate_orphan_image_set)
@@ -221,6 +229,7 @@ def garbage_collect_repo(repo, extra_candidate_set=None):
                                         ~(Image.id << referenced_candidates)))
 
       image_ids_to_remove = [candidate.id for candidate in unreferenced_candidates]
+      making_progress = bool(len(image_ids_to_remove))
       if len(image_ids_to_remove) == 0:
         # No more candidates to remove.
         break
@@ -254,12 +263,12 @@ def garbage_collect_repo(repo, extra_candidate_set=None):
         logger.info('Could not GC images %s; will try again soon', image_ids_to_remove)
         return False
 
-      # Add the images to the removed set and remove them from the candidate set.
-      all_images_removed.update(image_ids_to_remove)
-      all_storage_id_whitelist.update(storage_id_whitelist)
-      all_unreferenced_candidates.update(unreferenced_candidates)
+    # Add the images to the removed set and remove them from the candidate set.
+    all_images_removed.update(image_ids_to_remove)
+    all_storage_id_whitelist.update(storage_id_whitelist)
+    all_unreferenced_candidates.update(unreferenced_candidates)
 
-      candidate_orphan_image_set.difference_update(image_ids_to_remove)
+    candidate_orphan_image_set.difference_update(image_ids_to_remove)
 
   # If any images were removed, GC any orphaned storages.
   if len(all_images_removed) > 0: