diff --git a/src/v1/recaptcha_enterprise_service_client.ts b/src/v1/recaptcha_enterprise_service_client.ts
index 75e142c..f2f96b2 100644
--- a/src/v1/recaptcha_enterprise_service_client.ts
+++ b/src/v1/recaptcha_enterprise_service_client.ts
@@ -141,6 +141,8 @@ export class RecaptchaEnterpriseServiceClient {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest') {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);
diff --git a/src/v1beta1/recaptcha_enterprise_service_v1_beta1_client.ts b/src/v1beta1/recaptcha_enterprise_service_v1_beta1_client.ts
index 5197dcc..7d3bd29 100644
--- a/src/v1beta1/recaptcha_enterprise_service_v1_beta1_client.ts
+++ b/src/v1beta1/recaptcha_enterprise_service_v1_beta1_client.ts
@@ -141,6 +141,8 @@ export class RecaptchaEnterpriseServiceV1Beta1Client {
     }
     if (!opts.fallback) {
       clientHeader.push(`grpc/${this._gaxGrpc.grpcVersion}`);
+    } else if (opts.fallback === 'rest') {
+      clientHeader.push(`rest/${this._gaxGrpc.grpcVersion}`);
     }
     if (opts.libName && opts.libVersion) {
       clientHeader.push(`${opts.libName}/${opts.libVersion}`);