--- a/taskcluster/taskgraph/transforms/l10n.py
+++ b/taskcluster/taskgraph/transforms/l10n.py
@@ -278,17 +278,17 @@ def handle_keyed_by(config, jobs):
         for field in fields:
             resolve_keyed_by(item=job, field=field, item_name=job['name'])
         yield job
 
 
 @transforms.add
 def all_locales_attribute(config, jobs):
     for job in jobs:
-        locales_platform = job['attributes']['build_platform'].rstrip("-nightly")
+        locales_platform = job['attributes']['build_platform'].replace("-nightly", "")
         locales_with_changesets = _parse_locales_file(job["locales-file"],
                                                       platform=locales_platform)
         locales_with_changesets = _remove_locales(locales_with_changesets,
                                                   to_remove=job['ignore-locales'])
 
         locales = sorted(locales_with_changesets.keys())
         attributes = job.setdefault('attributes', {})
         attributes["all_locales"] = locales