diff --git a/lib/synth-audio.js b/lib/synth-audio.js
index 34358b7..210aa89 100644
--- a/lib/synth-audio.js
+++ b/lib/synth-audio.js
@@ -85,7 +85,7 @@ async function synthAudio(client, logger, stats, { account_sid,
   logger = logger || noopLogger;
 
   assert.ok(['google', 'aws', 'polly', 'microsoft',
-    'wellsaid', 'nuance', 'nvidia', 'ibm', 'elevenlabs', 'whisper', 'deepgram'].includes(vendor) ||
+    'wellsaid', 'nuance', 'nvidia', 'ibm', 'elevenlabs', 'whisper', 'deepgram', 'playht'].includes(vendor) ||
   vendor.startsWith('custom'),
   `synthAudio supported vendors are google, aws, microsoft, nuance, nvidia and wellsaid, not ${vendor}`);
   if ('google' === vendor) {