--- a/taskcluster/taskgraph/transforms/nightly_l10n_signing.py
+++ b/taskcluster/taskgraph/transforms/nightly_l10n_signing.py
@@ -63,9 +63,13 @@ def make_signing_description(config, job
 
         # add the chunk number to the TH symbol
         symbol = 'Ns{}'.format(dep_job.attributes.get('l10n_chunk'))
         group = 'tc-L10n'
 
         job['treeherder'] = {
             'symbol': join_symbol(group, symbol),
         }
+
+        # Funsize listens for this to know when to start generating partial updates.
+        job['routes'] = " project.releng.funsize.date.level-3"
+
         yield job