diff --git a/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1/stub/TextToSpeechStubSettings.java b/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1/stub/TextToSpeechStubSettings.java
index 0cd4fb00..c7d0b23f 100644
--- a/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1/stub/TextToSpeechStubSettings.java
+++ b/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1/stub/TextToSpeechStubSettings.java
@@ -119,6 +119,11 @@ public static String getDefaultEndpoint() {
     return "texttospeech.googleapis.com:443";
   }
 
+  /** Returns the default mTLS service endpoint. */
+  public static String getDefaultMtlsEndpoint() {
+    return "texttospeech.mtls.googleapis.com:443";
+  }
+
   /** Returns the default service scopes. */
   public static List<String> getDefaultServiceScopes() {
     return DEFAULT_SERVICE_SCOPES;
@@ -244,6 +249,8 @@ private static Builder createDefault() {
       builder.setCredentialsProvider(defaultCredentialsProviderBuilder().build());
       builder.setInternalHeaderProvider(defaultApiClientHeaderProviderBuilder().build());
       builder.setEndpoint(getDefaultEndpoint());
+      builder.setMtlsEndpoint(getDefaultMtlsEndpoint());
+      builder.setSwitchToMtlsEndpointAllowed(true);
 
       return initDefaults(builder);
     }
diff --git a/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1beta1/stub/TextToSpeechStubSettings.java b/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1beta1/stub/TextToSpeechStubSettings.java
index 24f8ed51..6de0fb2c 100644
--- a/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1beta1/stub/TextToSpeechStubSettings.java
+++ b/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1beta1/stub/TextToSpeechStubSettings.java
@@ -120,6 +120,11 @@ public static String getDefaultEndpoint() {
     return "texttospeech.googleapis.com:443";
   }
 
+  /** Returns the default mTLS service endpoint. */
+  public static String getDefaultMtlsEndpoint() {
+    return "texttospeech.mtls.googleapis.com:443";
+  }
+
   /** Returns the default service scopes. */
   public static List<String> getDefaultServiceScopes() {
     return DEFAULT_SERVICE_SCOPES;
@@ -245,6 +250,8 @@ private static Builder createDefault() {
       builder.setCredentialsProvider(defaultCredentialsProviderBuilder().build());
       builder.setInternalHeaderProvider(defaultApiClientHeaderProviderBuilder().build());
       builder.setEndpoint(getDefaultEndpoint());
+      builder.setMtlsEndpoint(getDefaultMtlsEndpoint());
+      builder.setSwitchToMtlsEndpointAllowed(true);
 
       return initDefaults(builder);
     }
diff --git a/synth.metadata b/synth.metadata
index cd1d7bf3..b8caf36b 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -4,23 +4,23 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-texttospeech.git",
-        "sha": "652cfdd983680af78060bb93a2f2da9c5e77da21"
+        "sha": "ac733583b6593eeede99215d2309b3e8c898664c"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "9e3105549a35520f215359065c11e8dce15e18af",
-        "internalRef": "378266372"
+        "sha": "08c4eeb531c01ad031134dca94b18e3f7dd35902",
+        "internalRef": "378718217"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "9e3105549a35520f215359065c11e8dce15e18af",
-        "internalRef": "378266372"
+        "sha": "08c4eeb531c01ad031134dca94b18e3f7dd35902",
+        "internalRef": "378718217"
       }
     },
     {