diff --git a/service/collector.go b/service/collector.go
index 6f84b98eb1c..b7e32dc7532 100644
--- a/service/collector.go
+++ b/service/collector.go
@@ -61,7 +61,7 @@ func (s State) String() string {
 	case Closed:
 		return "Closed"
 	}
-	return ""
+	return "UNKNOWN"
 }
 
 // (Internal note) Collector Lifecycle: