diff --git a/src/v1/device_manager_client.ts b/src/v1/device_manager_client.ts
index e1edb6e9..008a8d9e 100644
--- a/src/v1/device_manager_client.ts
+++ b/src/v1/device_manager_client.ts
@@ -140,6 +140,8 @@ export class DeviceManagerClient {
     }
     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}`);