diff --git a/packages/google-devtools-cloudbuild/src/v1/cloud_build_client.ts b/packages/google-devtools-cloudbuild/src/v1/cloud_build_client.ts
index cc78c8aa2bf..b78c9c9a06c 100644
--- a/packages/google-devtools-cloudbuild/src/v1/cloud_build_client.ts
+++ b/packages/google-devtools-cloudbuild/src/v1/cloud_build_client.ts
@@ -149,6 +149,8 @@ export class CloudBuildClient {
     }
     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}`);