diff --git a/inventory_provider/tasks/worker.py b/inventory_provider/tasks/worker.py
index d5687e4e37649ea2eb09fb813a163c0b53dcf05f..704a76437fbd75b9d7dcb7c0e1521ad2e38be44e 100644
--- a/inventory_provider/tasks/worker.py
+++ b/inventory_provider/tasks/worker.py
@@ -717,7 +717,7 @@ def _build_subnet_db(update_callback=lambda s: None):
 
     rp = r.pipeline()
     for k, v in subnets.items():
-        rp.set('subnets:' + k, json.dumps(v))
+        rp.set(f'subnets:{k}', json.dumps(v))
     rp.execute()