diff --git a/lib/smstools-config/queues-and-providers.js b/lib/smstools-config/queues-and-providers.js
index 5e3573c..d1847bf 100644
--- a/lib/smstools-config/queues-and-providers.js
+++ b/lib/smstools-config/queues-and-providers.js
@@ -71,11 +71,13 @@ 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);
             hasProviders = true;
+        } else {
+            logger.verbose(`QUEUES-AND-PROVIDERS: DEBUG: ${queue.name} does not have prefix`);
         }
     }