diff --git a/src/common-grpc/service.ts b/src/common-grpc/service.ts
index 24e84b884..08f5642d7 100644
--- a/src/common-grpc/service.ts
+++ b/src/common-grpc/service.ts
@@ -417,6 +417,12 @@ export class GrpcService extends Service {
 
     this.maxRetries = options.maxRetries;
     this.userAgent = util.getUserAgentFromPackageJson(config.packageJson);
+
+    if (this.providedUserAgent) {
+      this.userAgent = `${this.providedUserAgent} ${this.userAgent}`;
+    }
+    options['grpc.primary_user_agent'] = this.userAgent;
+
     this.activeServiceMap_ = new Map();
     this.protos = {};
     const protoServices = config.protoServices;
diff --git a/test/common/service.ts b/test/common/service.ts
index bb5d417df..293f98d0f 100644
--- a/test/common/service.ts
+++ b/test/common/service.ts
@@ -402,6 +402,18 @@ describe('GrpcService', () => {
       assert.strictEqual(grpcService.userAgent, userAgent);
     });
 
+    it('should set the primary_user_agent from user-agent', () => {
+      const userAgent = 'user-agent/0.0.0';
+
+      getUserAgentFromPackageJsonOverride = packageJson => {
+        assert.strictEqual(packageJson, CONFIG.packageJson);
+        return userAgent;
+      };
+
+      new GrpcService(CONFIG, OPTIONS);
+      assert.strictEqual(OPTIONS['grpc.primary_user_agent'], userAgent);
+    });
+
     it('should localize the service', () => {
       assert.deepStrictEqual(
         Object.keys(grpcService.protos),