diff --git a/src/core.ts b/src/core.ts
index afa103a..43d61f7 100644
--- a/src/core.ts
+++ b/src/core.ts
@@ -288,7 +288,7 @@ export class DnsCore {
    private onMessage: ListenerCallback = async (data: Buffer, sender: string, r) => {
       let max_size = 128 * 1024;
       let stream = true;
-      if (typeof r === "number") {
+      if (!r || typeof r === "number") {
          max_size = r;
          stream = false;
       }