diff --git a/run.go b/run.go
index e4c0f84..8af23f4 100644
--- a/run.go
+++ b/run.go
@@ -277,6 +277,6 @@ func supportsConcurrency(format string) bool {
 	case "events", "pretty", "cucumber":
 		return false
 	default:
-		return false
+		return true // enables concurrent custom formatters to work
 	}
 }