diff --git a/relaycfg/cfg.go b/relaycfg/cfg.go
index 5302753..e92a77b 100644
--- a/relaycfg/cfg.go
+++ b/relaycfg/cfg.go
@@ -96,7 +96,9 @@ func (c *C) Validate() error {
 		}
 	} else {
 		for _, sc := range c.Contracts {
-			sc.UpgradeChannel = "default"
+			if sc.UpgradeChannel == "" {
+				sc.UpgradeChannel = "default"
+			}
 		}
 	}