diff --git a/photologue_custom/management/commands/duplicate.py b/photologue_custom/management/commands/duplicate.py
index 634e057..93a9150 100644
--- a/photologue_custom/management/commands/duplicate.py
+++ b/photologue_custom/management/commands/duplicate.py
@@ -19,15 +19,14 @@ class Command(BaseCommand):
         if options['all']:
             galleries = Gallery.objects.all()
         else:
+            galleries = []
             for slug in options['slugs']:
-                for gallery in Gallery.objects.all():
-                    if gallery.slug == slug:
-                        galleries += [gallery]
-                        break
-                else:
-                    raise CommandError(
-                        'Slug {} does not correspond to a gallery in the database.'.format(slug))
-                    print('error')
+                gallery_query = Gallery.objects.filter(slug=slug)
+                if not gallery_query:
+                    raise CommandError(f"Slug {slug} does not correspond to a "
+                                       "gallery in the database.")
+                galleries += gallery_query
+
         # Find duplicates in all galleries
         for gallery in galleries:
             duplicates = find_duplicate(gallery)