diff --git a/lib/synth-audio.js b/lib/synth-audio.js
index e88a93c..a8c35b2 100644
--- a/lib/synth-audio.js
+++ b/lib/synth-audio.js
@@ -257,9 +257,9 @@ const synthGoogle = async(logger, {credentials, stats, language, voice, gender,
   const client = new ttsGoogle.TextToSpeechClient(credentials);
   const opts = {
     voice: {
-      name: voice,
+      ...( typeof voice === 'string' && {name: voice, ssmlGender: gender || 'SSML_VOICE_GENDER_UNSPECIFIED'}),
+      ...( typeof voice === 'object' && {custom_voice: voice}),
       languageCode: language,
-      ssmlGender: gender || 'SSML_VOICE_GENDER_UNSPECIFIED'
     },
     audioConfig: {audioEncoding: 'MP3'}
   };
diff --git a/test/synth.js b/test/synth.js
index 6ef5b20..d6920a0 100644
--- a/test/synth.js
+++ b/test/synth.js
@@ -79,6 +79,40 @@ test('Google speech synth tests', async(t) => {
   client.quit();
 });
 
+test('Google speech Custom voice synth tests', async(t) => {
+  const fn = require('..');
+  const {synthAudio, client} = fn(opts, logger);
+
+  if (!process.env.GCP_CUSTOM_VOICE_FILE && !process.env.GCP_CUSTOM_VOICE_JSON_KEY || !process.env.GCP_CUSTOM_VOICE_MODEL) {
+    t.pass('skipping google speech synth tests since neither GCP_CUSTOM_VOICE_FILE nor GCP_CUSTOM_VOICE_JSON_KEY provided, GCP_CUSTOM_VOICE_MODEL is not provided');
+    return t.end();
+  }
+  try {
+    const str = process.env.GCP_CUSTOM_VOICE_JSON_KEY || fs.readFileSync(process.env.GCP_CUSTOM_VOICE_FILE);
+    const creds = JSON.parse(str);
+    let opts = await synthAudio(stats, {
+      vendor: 'google',
+      credentials: {
+        credentials: {
+          client_email: creds.client_email,
+          private_key: creds.private_key,
+        },
+      },
+      language: 'en-AU',
+      text: 'This is a test.  This is only a test',
+      voice: {
+        reportedUsage:"REALTIME",
+        model: process.env.GCP_CUSTOM_VOICE_MODEL
+      }
+    });
+    t.ok(!opts.servedFromCache, `successfully synthesized google custom voice audio to ${opts.filePath}`);
+  } catch (err) {
+    console.error(err);
+    t.end(err);
+  }
+  client.quit();
+});
+
 test('AWS speech synth tests', async(t) => {
   const fn = require('..');
   const {synthAudio, client} = fn(opts, logger);