diff --git a/src/lib/onvif.ts b/src/lib/onvif.ts
index 93b5ebc..6e52bbf 100644
--- a/src/lib/onvif.ts
+++ b/src/lib/onvif.ts
@@ -45,6 +45,7 @@ const WS_DISCOVERY_PORT = 3702;
 const MIN_SWEEP_PREFIX = 20;
 const SWEEP_BATCH_SIZE = 64;
 const SWEEP_BATCH_DELAY_MS = 15;
+const CONTINUE_NO_PREFIX: {shouldContinue: boolean, prefix: number} = {shouldContinue: true, prefix: 0};
 
 // Discovery is an EventEmitter singleton that emits "error" for malformed replies;
 // without a listener Node would throw and take down the server process.
@@ -119,14 +120,9 @@ function localSubnetHosts(): string[] {
   const hosts = new Set<string>();
   for (const addrs of Object.values(os.networkInterfaces())) {
     for (const addr of addrs ?? []) {
-      if (addr.family !== "IPv4" || addr.internal || !addr.cidr) continue;
-      if (addr.address.startsWith("169.254.")) continue;
-      const prefix = Number(addr.cidr.split("/")[1]);
-      if (prefix < MIN_SWEEP_PREFIX || prefix > 30) {
-        console.warn(`[onvif] skipping unicast sweep of ${addr.cidr}`);
-        continue;
-      }
-      const mask = (0xffffffff << (32 - prefix)) >>> 0;
+      const checkResult = checkAddr(addr);
+      if (checkResult.shouldContinue) continue;
+      const mask = (0xffffffff << (32 - checkResult.prefix)) >>> 0;
       const network = (ipToInt(addr.address) & mask) >>> 0;
       const broadcast = (network | ~mask) >>> 0;
       for (let n = network + 1; n < broadcast; n++) {
@@ -137,6 +133,18 @@ function localSubnetHosts(): string[] {
   }
   return [...hosts];
 }
+function checkAddr(addr: os.NetworkInterfaceInfo): {shouldContinue: boolean, prefix: number} {
+
+  if (addr.family !== "IPv4" || addr.internal || !addr.cidr) return CONTINUE_NO_PREFIX;
+  if (addr.address.startsWith("169.254.")) return CONTINUE_NO_PREFIX;
+  const prefix = Number(addr.cidr.split("/")[1]);
+  if (prefix < MIN_SWEEP_PREFIX || prefix > 30) {
+    console.warn(`[onvif] skipping unicast sweep of ${addr.cidr}`);
+    return CONTINUE_NO_PREFIX;
+  }
+
+  return {shouldContinue: false, prefix: prefix};
+}
 
 function probeMessage(messageId: string): Buffer {
   return Buffer.from(