diff --git a/lib/smstools-config/queues-and-providers.js b/lib/smstools-config/queues-and-providers.js
index d1847bf..3ef30f9 100644
--- a/lib/smstools-config/queues-and-providers.js
+++ b/lib/smstools-config/queues-and-providers.js
@@ -71,7 +71,7 @@ exports.dump = async (mkdirIfQueueDirNotExists) => {
         configLines.push(line);
         hasQueues = true;
 
-        const hasPrefix = !(queue.prefix && queue.prefix.length);
+        const hasPrefix = queue.prefix && queue.prefix.length;
         if (hasPrefix) {
             const providerLine = `${queue.name} = ${queue.prefix.join(', ')}`;
             providerLines.push(providerLine);