diff --git a/imageroot/loki-config.yaml b/imageroot/loki-config.yaml
index 79e8e0a..02ffc35 100644
--- a/imageroot/loki-config.yaml
+++ b/imageroot/loki-config.yaml
@@ -49,7 +49,7 @@ chunk_store_config:
 
 table_manager:
   retention_deletes_enabled: false
-  retention_period: ${LOKI_RETENTION_PERIOD:365}d
+  retention_period: ${LOKI_RETENTION_PERIOD:-365}d
 
 ruler:
   storage: