diff --git a/examples/generated/proto/examplecom/simple_service_pb_service.d.ts b/examples/generated/proto/examplecom/simple_service_pb_service.d.ts
index 351e7360..02f17987 100644
--- a/examples/generated/proto/examplecom/simple_service_pb_service.d.ts
+++ b/examples/generated/proto/examplecom/simple_service_pb_service.d.ts
@@ -80,13 +80,13 @@ interface RequestStream<T> {
   on(type: 'end', handler: () => void): RequestStream<T>;
   on(type: 'status', handler: (status: Status) => void): RequestStream<T>;
 }
-interface BidirectionalStream<T> {
-  write(message: T): BidirectionalStream<T>;
+interface BidirectionalStream<Req, Res> {
+  write(message: Req): BidirectionalStream<Req, Res>;
   end(): void;
   cancel(): void;
-  on(type: 'data', handler: (message: T) => void): BidirectionalStream<T>;
-  on(type: 'end', handler: () => void): BidirectionalStream<T>;
-  on(type: 'status', handler: (status: Status) => void): BidirectionalStream<T>;
+  on(type: 'data', handler: (message: Res) => void): BidirectionalStream<Req, Res>;
+  on(type: 'end', handler: () => void): BidirectionalStream<Req, Res>;
+  on(type: 'status', handler: (status: Status) => void): BidirectionalStream<Req, Res>;
 }
 
 export class SimpleServiceClient {
@@ -104,7 +104,7 @@ export class SimpleServiceClient {
   ): UnaryResponse;
   doServerStream(requestMessage: proto_examplecom_simple_service_pb.StreamRequest, metadata?: grpc.Metadata): ResponseStream<proto_othercom_external_child_message_pb.ExternalChildMessage>;
   doClientStream(metadata?: grpc.Metadata): RequestStream<proto_examplecom_simple_service_pb.StreamRequest>;
-  doBidiStream(metadata?: grpc.Metadata): BidirectionalStream<proto_othercom_external_child_message_pb.ExternalChildMessage>;
+  doBidiStream(metadata?: grpc.Metadata): BidirectionalStream<proto_examplecom_simple_service_pb.StreamRequest, proto_othercom_external_child_message_pb.ExternalChildMessage>;
   delete(
     requestMessage: proto_examplecom_simple_service_pb.UnaryRequest,
     metadata: grpc.Metadata,
diff --git a/examples/generated/proto/orphan_pb_service.d.ts b/examples/generated/proto/orphan_pb_service.d.ts
index ab177ea5..ee2a88eb 100644
--- a/examples/generated/proto/orphan_pb_service.d.ts
+++ b/examples/generated/proto/orphan_pb_service.d.ts
@@ -48,13 +48,13 @@ interface RequestStream<T> {
   on(type: 'end', handler: () => void): RequestStream<T>;
   on(type: 'status', handler: (status: Status) => void): RequestStream<T>;
 }
-interface BidirectionalStream<T> {
-  write(message: T): BidirectionalStream<T>;
+interface BidirectionalStream<Req, Res> {
+  write(message: Req): BidirectionalStream<Req, Res>;
   end(): void;
   cancel(): void;
-  on(type: 'data', handler: (message: T) => void): BidirectionalStream<T>;
-  on(type: 'end', handler: () => void): BidirectionalStream<T>;
-  on(type: 'status', handler: (status: Status) => void): BidirectionalStream<T>;
+  on(type: 'data', handler: (message: Res) => void): BidirectionalStream<Req, Res>;
+  on(type: 'end', handler: () => void): BidirectionalStream<Req, Res>;
+  on(type: 'status', handler: (status: Status) => void): BidirectionalStream<Req, Res>;
 }
 
 export class OrphanServiceClient {
diff --git a/src/service/grpcweb.ts b/src/service/grpcweb.ts
index 6c4f9d1f..f4dba71a 100644
--- a/src/service/grpcweb.ts
+++ b/src/service/grpcweb.ts
@@ -1,14 +1,14 @@
-import {filePathToPseudoNamespace, normaliseFieldObjectName, replaceProtoSuffix, getPathToRoot} from "../util";
-import {ExportMap} from "../ExportMap";
-import {Printer} from "../Printer";
-import {CodePrinter} from "../CodePrinter";
+import { filePathToPseudoNamespace, normaliseFieldObjectName, replaceProtoSuffix, getPathToRoot } from "../util";
+import { ExportMap } from "../ExportMap";
+import { Printer } from "../Printer";
+import { CodePrinter } from "../CodePrinter";
 import {
   FileDescriptorProto, MethodDescriptorProto,
   ServiceDescriptorProto
 } from "google-protobuf/google/protobuf/descriptor_pb";
-import {WellKnownTypesMap} from "../WellKnown";
-import {getFieldType, MESSAGE_TYPE} from "../ts/FieldTypes";
-import {CodeGeneratorResponse} from "google-protobuf/google/protobuf/compiler/plugin_pb";
+import { WellKnownTypesMap } from "../WellKnown";
+import { getFieldType, MESSAGE_TYPE } from "../ts/FieldTypes";
+import { CodeGeneratorResponse } from "google-protobuf/google/protobuf/compiler/plugin_pb";
 
 export function generateGrpcWebService(filename: string, descriptor: FileDescriptorProto, exportMap: ExportMap): CodeGeneratorResponse.File[] {
   return [
@@ -142,7 +142,7 @@ class GrpcWebServiceDescriptor {
       namespace: filePathToPseudoNamespace(this.filename),
       path: `${this.pathToRoot}${replaceProtoSuffix(this.filename)}`,
     };
-    return [ hostProto ].concat(dependencies);
+    return [hostProto].concat(dependencies);
   }
 
   get services(): RPCDescriptor[] {
@@ -222,13 +222,13 @@ function generateTypescriptDefinition(fileDescriptor: FileDescriptorProto, expor
   printer.printIndentedLn(`on(type: 'end', handler: () => void): RequestStream<T>;`);
   printer.printIndentedLn(`on(type: 'status', handler: (status: Status) => void): RequestStream<T>;`);
   printer.printLn(`}`);
-  printer.printLn(`interface BidirectionalStream<T> {`);
-  printer.printIndentedLn(`write(message: T): BidirectionalStream<T>;`);
+  printer.printLn(`interface BidirectionalStream<Req, Res> {`);
+  printer.printIndentedLn(`write(message: Req): BidirectionalStream<Req, Res>;`);
   printer.printIndentedLn(`end(): void;`);
   printer.printIndentedLn(`cancel(): void;`);
-  printer.printIndentedLn(`on(type: 'data', handler: (message: T) => void): BidirectionalStream<T>;`);
-  printer.printIndentedLn(`on(type: 'end', handler: () => void): BidirectionalStream<T>;`);
-  printer.printIndentedLn(`on(type: 'status', handler: (status: Status) => void): BidirectionalStream<T>;`);
+  printer.printIndentedLn(`on(type: 'data', handler: (message: Res) => void): BidirectionalStream<Req, Res>;`);
+  printer.printIndentedLn(`on(type: 'end', handler: () => void): BidirectionalStream<Req, Res>;`);
+  printer.printIndentedLn(`on(type: 'status', handler: (status: Status) => void): BidirectionalStream<Req, Res>;`);
   printer.printLn(`}`);
   printer.printEmptyLn();
 
@@ -301,10 +301,10 @@ function printServiceStub(methodPrinter: Printer, service: RPCDescriptor) {
   const printer = new CodePrinter(0, methodPrinter);
 
   printer
-           .printLn(`function ${service.name}Client(serviceHost, options) {`)
+    .printLn(`function ${service.name}Client(serviceHost, options) {`)
     .indent().printLn(`this.serviceHost = serviceHost;`)
-             .printLn(`this.options = options || {};`)
-  .dedent().printLn(`}`)
+    .printLn(`this.options = options || {};`)
+    .dedent().printLn(`}`)
     .printEmptyLn();
 
   service.methods.forEach((method: RPCMethodDescriptor) => {
@@ -324,180 +324,180 @@ function printServiceStub(methodPrinter: Printer, service: RPCDescriptor) {
 
 function printUnaryStubMethod(printer: CodePrinter, method: RPCMethodDescriptor) {
   printer
-             .printLn(`${method.serviceName}Client.prototype.${method.nameAsCamelCase} = function ${method.functionName}(requestMessage, metadata, callback) {`)
-      .indent().printLn(`if (arguments.length === 2) {`)
-        .indent().printLn(`callback = arguments[1];`)
-      .dedent().printLn("}")
-               .printLn(`var client = grpc.unary(${method.serviceName}.${method.nameAsPascalCase}, {`)
-        .indent().printLn(`request: requestMessage,`)
-                 .printLn(`host: this.serviceHost,`)
-                 .printLn(`metadata: metadata,`)
-                 .printLn(`transport: this.options.transport,`)
-                 .printLn(`debug: this.options.debug,`)
-                 .printLn(`onEnd: function (response) {`)
-          .indent().printLn(`if (callback) {`)
-            .indent().printLn(`if (response.status !== grpc.Code.OK) {`)
-              .indent().printLn(`var err = new Error(response.statusMessage);`)
-                       .printLn(`err.code = response.status;`)
-                       .printLn(`err.metadata = response.trailers;`)
-                       .printLn(`callback(err, null);`)
-            .dedent().printLn(`} else {`)
-              .indent().printLn(`callback(null, response.message);`)
-            .dedent().printLn(`}`)
-          .dedent().printLn(`}`)
-        .dedent().printLn(`}`)
-      .dedent().printLn(`});`)
-             .printLn(`return {`)
-      .indent().printLn(`cancel: function () {`)
-        .indent().printLn(`callback = null;`)
-                 .printLn(`client.close();`)
-      .dedent().printLn(`}`)
+    .printLn(`${method.serviceName}Client.prototype.${method.nameAsCamelCase} = function ${method.functionName}(requestMessage, metadata, callback) {`)
+    .indent().printLn(`if (arguments.length === 2) {`)
+    .indent().printLn(`callback = arguments[1];`)
+    .dedent().printLn("}")
+    .printLn(`var client = grpc.unary(${method.serviceName}.${method.nameAsPascalCase}, {`)
+    .indent().printLn(`request: requestMessage,`)
+    .printLn(`host: this.serviceHost,`)
+    .printLn(`metadata: metadata,`)
+    .printLn(`transport: this.options.transport,`)
+    .printLn(`debug: this.options.debug,`)
+    .printLn(`onEnd: function (response) {`)
+    .indent().printLn(`if (callback) {`)
+    .indent().printLn(`if (response.status !== grpc.Code.OK) {`)
+    .indent().printLn(`var err = new Error(response.statusMessage);`)
+    .printLn(`err.code = response.status;`)
+    .printLn(`err.metadata = response.trailers;`)
+    .printLn(`callback(err, null);`)
+    .dedent().printLn(`} else {`)
+    .indent().printLn(`callback(null, response.message);`)
+    .dedent().printLn(`}`)
+    .dedent().printLn(`}`)
+    .dedent().printLn(`}`)
+    .dedent().printLn(`});`)
+    .printLn(`return {`)
+    .indent().printLn(`cancel: function () {`)
+    .indent().printLn(`callback = null;`)
+    .printLn(`client.close();`)
+    .dedent().printLn(`}`)
     .dedent().printLn(`};`)
-  .dedent().printLn(`};`);
+    .dedent().printLn(`};`);
 }
 
 function printServerStreamStubMethod(printer: CodePrinter, method: RPCMethodDescriptor) {
   printer
-           .printLn(`${method.serviceName}Client.prototype.${method.nameAsCamelCase} = function ${method.functionName}(requestMessage, metadata) {`)
+    .printLn(`${method.serviceName}Client.prototype.${method.nameAsCamelCase} = function ${method.functionName}(requestMessage, metadata) {`)
     .indent().printLn(`var listeners = {`)
-      .indent().printLn(`data: [],`)
-               .printLn(`end: [],`)
-               .printLn(`status: []`)
+    .indent().printLn(`data: [],`)
+    .printLn(`end: [],`)
+    .printLn(`status: []`)
     .dedent().printLn(`};`)
-             .printLn(`var client = grpc.invoke(${method.serviceName}.${method.nameAsPascalCase}, {`)
-      .indent().printLn(`request: requestMessage,`)
-               .printLn(`host: this.serviceHost,`)
-               .printLn(`metadata: metadata,`)
-               .printLn(`transport: this.options.transport,`)
-               .printLn(`debug: this.options.debug,`)
-               .printLn(`onMessage: function (responseMessage) {`)
-        .indent().printLn(`listeners.data.forEach(function (handler) {`)
-          .indent().printLn(`handler(responseMessage);`)
-        .dedent().printLn(`});`)
-      .dedent().printLn(`},`)
-               .printLn(`onEnd: function (status, statusMessage, trailers) {`)
-        .indent().printLn(`listeners.end.forEach(function (handler) {`)
-          .indent().printLn(`handler();`)
-        .dedent().printLn(`});`)
-                 .printLn(`listeners.status.forEach(function (handler) {`)
-          .indent().printLn(`handler({ code: status, details: statusMessage, metadata: trailers });`)
-        .dedent().printLn(`});`)
-                 .printLn(`listeners = null;`)
-      .dedent().printLn(`}`)
+    .printLn(`var client = grpc.invoke(${method.serviceName}.${method.nameAsPascalCase}, {`)
+    .indent().printLn(`request: requestMessage,`)
+    .printLn(`host: this.serviceHost,`)
+    .printLn(`metadata: metadata,`)
+    .printLn(`transport: this.options.transport,`)
+    .printLn(`debug: this.options.debug,`)
+    .printLn(`onMessage: function (responseMessage) {`)
+    .indent().printLn(`listeners.data.forEach(function (handler) {`)
+    .indent().printLn(`handler(responseMessage);`)
+    .dedent().printLn(`});`)
+    .dedent().printLn(`},`)
+    .printLn(`onEnd: function (status, statusMessage, trailers) {`)
+    .indent().printLn(`listeners.end.forEach(function (handler) {`)
+    .indent().printLn(`handler();`)
+    .dedent().printLn(`});`)
+    .printLn(`listeners.status.forEach(function (handler) {`)
+    .indent().printLn(`handler({ code: status, details: statusMessage, metadata: trailers });`)
+    .dedent().printLn(`});`)
+    .printLn(`listeners = null;`)
+    .dedent().printLn(`}`)
     .dedent().printLn(`});`)
-             .printLn(`return {`)
-      .indent().printLn(`on: function (type, handler) {`)
-        .indent().printLn(`listeners[type].push(handler);`)
-                 .printLn(`return this;`)
-      .dedent().printLn(`},`)
-               .printLn(`cancel: function () {`)
-        .indent().printLn(`listeners = null;`)
-                 .printLn(`client.close();`)
-      .dedent().printLn(`}`)
+    .printLn(`return {`)
+    .indent().printLn(`on: function (type, handler) {`)
+    .indent().printLn(`listeners[type].push(handler);`)
+    .printLn(`return this;`)
+    .dedent().printLn(`},`)
+    .printLn(`cancel: function () {`)
+    .indent().printLn(`listeners = null;`)
+    .printLn(`client.close();`)
+    .dedent().printLn(`}`)
     .dedent().printLn(`};`)
-  .dedent().printLn(`};`);
+    .dedent().printLn(`};`);
 }
 
 function printClientStreamStubMethod(printer: CodePrinter, method: RPCMethodDescriptor) {
   printer
-           .printLn(`${method.serviceName}Client.prototype.${method.nameAsCamelCase} = function ${method.functionName}(metadata) {`)
+    .printLn(`${method.serviceName}Client.prototype.${method.nameAsCamelCase} = function ${method.functionName}(metadata) {`)
     .indent().printLn(`var listeners = {`)
-      .indent().printLn(`end: [],`)
-               .printLn(`status: []`)
+    .indent().printLn(`end: [],`)
+    .printLn(`status: []`)
     .dedent().printLn(`};`)
-             .printLn(`var client = grpc.client(${method.serviceName}.${method.nameAsPascalCase}, {`)
-      .indent().printLn(`host: this.serviceHost,`)
-               .printLn(`metadata: metadata,`)
-               .printLn(`transport: this.options.transport`)
+    .printLn(`var client = grpc.client(${method.serviceName}.${method.nameAsPascalCase}, {`)
+    .indent().printLn(`host: this.serviceHost,`)
+    .printLn(`metadata: metadata,`)
+    .printLn(`transport: this.options.transport`)
     .dedent().printLn(`});`)
-             .printLn(`client.onEnd(function (status, statusMessage, trailers) {`)
-      .indent().printLn(`listeners.end.forEach(function (handler) {`)
-        .indent().printLn(`handler();`)
-      .dedent().printLn(`});`)
-               .printLn(`listeners.status.forEach(function (handler) {`)
-        .indent().printLn(`handler({ code: status, details: statusMessage, metadata: trailers });`)
-      .dedent().printLn(`});`)
-               .printLn(`listeners = null;`)
+    .printLn(`client.onEnd(function (status, statusMessage, trailers) {`)
+    .indent().printLn(`listeners.end.forEach(function (handler) {`)
+    .indent().printLn(`handler();`)
     .dedent().printLn(`});`)
-             .printLn(`return {`)
-      .indent().printLn(`on: function (type, handler) {`)
-        .indent().printLn(`listeners[type].push(handler);`)
-                 .printLn(`return this;`)
-      .dedent().printLn(`},`)
-               .printLn(`write: function (requestMessage) {`)
-        .indent().printLn(`if (!client.started) {`)
-          .indent().printLn(`client.start(metadata);`)
-        .dedent().printLn(`}`)
-                 .printLn(`client.send(requestMessage);`)
-                 .printLn(`return this;`)
-      .dedent().printLn(`},`)
-               .printLn(`end: function () {`)
-        .indent().printLn(`client.finishSend();`)
-      .dedent().printLn(`},`)
-               .printLn(`cancel: function () {`)
-        .indent().printLn(`listeners = null;`)
-                 .printLn(`client.close();`)
-      .dedent().printLn(`}`)
+    .printLn(`listeners.status.forEach(function (handler) {`)
+    .indent().printLn(`handler({ code: status, details: statusMessage, metadata: trailers });`)
+    .dedent().printLn(`});`)
+    .printLn(`listeners = null;`)
+    .dedent().printLn(`});`)
+    .printLn(`return {`)
+    .indent().printLn(`on: function (type, handler) {`)
+    .indent().printLn(`listeners[type].push(handler);`)
+    .printLn(`return this;`)
+    .dedent().printLn(`},`)
+    .printLn(`write: function (requestMessage) {`)
+    .indent().printLn(`if (!client.started) {`)
+    .indent().printLn(`client.start(metadata);`)
+    .dedent().printLn(`}`)
+    .printLn(`client.send(requestMessage);`)
+    .printLn(`return this;`)
+    .dedent().printLn(`},`)
+    .printLn(`end: function () {`)
+    .indent().printLn(`client.finishSend();`)
+    .dedent().printLn(`},`)
+    .printLn(`cancel: function () {`)
+    .indent().printLn(`listeners = null;`)
+    .printLn(`client.close();`)
+    .dedent().printLn(`}`)
     .dedent().printLn(`};`)
-  .dedent().printLn(`};`);
+    .dedent().printLn(`};`);
 }
 
 function printBidirectionalStubMethod(printer: CodePrinter, method: RPCMethodDescriptor) {
   printer
-           .printLn(`${method.serviceName}Client.prototype.${method.nameAsCamelCase} = function ${method.functionName}(metadata) {`)
+    .printLn(`${method.serviceName}Client.prototype.${method.nameAsCamelCase} = function ${method.functionName}(metadata) {`)
     .indent().printLn(`var listeners = {`)
-      .indent().printLn(`data: [],`)
-               .printLn(`end: [],`)
-               .printLn(`status: []`)
+    .indent().printLn(`data: [],`)
+    .printLn(`end: [],`)
+    .printLn(`status: []`)
     .dedent().printLn(`};`)
-             .printLn(`var client = grpc.client(${method.serviceName}.${method.nameAsPascalCase}, {`)
-      .indent().printLn(`host: this.serviceHost,`)
-               .printLn(`metadata: metadata,`)
-               .printLn(`transport: this.options.transport`)
+    .printLn(`var client = grpc.client(${method.serviceName}.${method.nameAsPascalCase}, {`)
+    .indent().printLn(`host: this.serviceHost,`)
+    .printLn(`metadata: metadata,`)
+    .printLn(`transport: this.options.transport`)
+    .dedent().printLn(`});`)
+    .printLn(`client.onEnd(function (status, statusMessage, trailers) {`)
+    .indent().printLn(`listeners.end.forEach(function (handler) {`)
+    .indent().printLn(`handler();`)
+    .dedent().printLn(`});`)
+    .printLn(`listeners.status.forEach(function (handler) {`)
+    .indent().printLn(`handler({ code: status, details: statusMessage, metadata: trailers });`)
     .dedent().printLn(`});`)
-             .printLn(`client.onEnd(function (status, statusMessage, trailers) {`)
-      .indent().printLn(`listeners.end.forEach(function (handler) {`)
-        .indent().printLn(`handler();`)
-      .dedent().printLn(`});`)
-               .printLn(`listeners.status.forEach(function (handler) {`)
-        .indent().printLn(`handler({ code: status, details: statusMessage, metadata: trailers });`)
-      .dedent().printLn(`});`)
-               .printLn(`listeners = null;`)
+    .printLn(`listeners = null;`)
     .dedent().printLn(`});`)
-             .printLn(`client.onMessage(function (message) {`)
-      .indent().printLn(`listeners.data.forEach(function (handler) {`)
-        .indent().printLn(`handler(message);`)
-      .dedent().printLn(`})`)
+    .printLn(`client.onMessage(function (message) {`)
+    .indent().printLn(`listeners.data.forEach(function (handler) {`)
+    .indent().printLn(`handler(message);`)
+    .dedent().printLn(`})`)
     .dedent().printLn(`});`)
-             .printLn(`client.start(metadata);`)
-             .printLn(`return {`)
-      .indent().printLn(`on: function (type, handler) {`)
-        .indent().printLn(`listeners[type].push(handler);`)
-                 .printLn(`return this;`)
-      .dedent().printLn(`},`)
-               .printLn(`write: function (requestMessage) {`)
-        .indent().printLn(`client.send(requestMessage);`)
-                 .printLn(`return this;`)
-      .dedent().printLn(`},`)
-               .printLn(`end: function () {`)
-        .indent().printLn(`client.finishSend();`)
-      .dedent().printLn(`},`)
-               .printLn(`cancel: function () {`)
-        .indent().printLn(`listeners = null;`)
-                 .printLn(`client.close();`)
-      .dedent().printLn(`}`)
+    .printLn(`client.start(metadata);`)
+    .printLn(`return {`)
+    .indent().printLn(`on: function (type, handler) {`)
+    .indent().printLn(`listeners[type].push(handler);`)
+    .printLn(`return this;`)
+    .dedent().printLn(`},`)
+    .printLn(`write: function (requestMessage) {`)
+    .indent().printLn(`client.send(requestMessage);`)
+    .printLn(`return this;`)
+    .dedent().printLn(`},`)
+    .printLn(`end: function () {`)
+    .indent().printLn(`client.finishSend();`)
+    .dedent().printLn(`},`)
+    .printLn(`cancel: function () {`)
+    .indent().printLn(`listeners = null;`)
+    .printLn(`client.close();`)
+    .dedent().printLn(`}`)
     .dedent().printLn(`};`)
-  .dedent().printLn(`};`);
+    .dedent().printLn(`};`);
 }
 
 function printServiceStubTypes(methodPrinter: Printer, service: RPCDescriptor) {
   const printer = new CodePrinter(0, methodPrinter);
 
   printer
-           .printLn(`export class ${service.name}Client {`)
+    .printLn(`export class ${service.name}Client {`)
     .indent().printLn(`readonly serviceHost: string;`)
-        .printEmptyLn()
-             .printLn(`constructor(serviceHost: string, options?: ServiceClientOptions);`);
+    .printEmptyLn()
+    .printLn(`constructor(serviceHost: string, options?: ServiceClientOptions);`);
 
   service.methods.forEach((method: RPCMethodDescriptor) => {
     if (method.requestStream && method.responseStream) {
@@ -515,14 +515,14 @@ function printServiceStubTypes(methodPrinter: Printer, service: RPCDescriptor) {
 
 function printUnaryStubMethodTypes(printer: CodePrinter, method: RPCMethodDescriptor) {
   printer
-             .printLn(`${method.nameAsCamelCase}(`)
-      .indent().printLn(`requestMessage: ${method.requestType},`)
-               .printLn(`metadata: grpc.Metadata,`)
-               .printLn(`callback: (error: ServiceError|null, responseMessage: ${method.responseType}|null) => void`)
+    .printLn(`${method.nameAsCamelCase}(`)
+    .indent().printLn(`requestMessage: ${method.requestType},`)
+    .printLn(`metadata: grpc.Metadata,`)
+    .printLn(`callback: (error: ServiceError|null, responseMessage: ${method.responseType}|null) => void`)
     .dedent().printLn(`): UnaryResponse;`)
-             .printLn(`${method.nameAsCamelCase}(`)
-      .indent().printLn(`requestMessage: ${method.requestType},`)
-               .printLn(`callback: (error: ServiceError|null, responseMessage: ${method.responseType}|null) => void`)
+    .printLn(`${method.nameAsCamelCase}(`)
+    .indent().printLn(`requestMessage: ${method.requestType},`)
+    .printLn(`callback: (error: ServiceError|null, responseMessage: ${method.responseType}|null) => void`)
     .dedent().printLn(`): UnaryResponse;`);
 }
 
@@ -535,5 +535,5 @@ function printClientStreamStubMethodTypes(printer: CodePrinter, method: RPCMetho
 }
 
 function printBidirectionalStubMethodTypes(printer: CodePrinter, method: RPCMethodDescriptor) {
-  printer.printLn(`${method.nameAsCamelCase}(metadata?: grpc.Metadata): BidirectionalStream<${method.responseType}>;`);
+  printer.printLn(`${method.nameAsCamelCase}(metadata?: grpc.Metadata): BidirectionalStream<${method.requestType}, ${method.responseType}>;`);
 }
diff --git a/test/integration/service/grpcweb.ts b/test/integration/service/grpcweb.ts
index f803aa87..bb863a94 100644
--- a/test/integration/service/grpcweb.ts
+++ b/test/integration/service/grpcweb.ts
@@ -453,7 +453,8 @@ describe("service/grpc-web", () => {
     });
 
     describe("bidirectional streaming", () => {
-      const [ payload ] = makePayloads("some value");
+      const payload = new StreamRequest();
+      payload.setSomeString("some value");
 
       it("should route the request to the expected endpoint", (done) => {
         let targetUrl = "";
@@ -496,7 +497,7 @@ describe("service/grpc-web", () => {
       it("should invoke onEnd before onStatus if the server ends the stream", (done) => {
         let onEndInvoked = false;
 
-        makeClient(new StubTransportBuilder().withMessages([ payload ]))
+        makeClient(new StubTransportBuilder().withMessages([payload]))
           .doBidiStream()
           .on("end", () => { onEndInvoked = true; })
           .on("status", () => {
@@ -535,7 +536,10 @@ describe("service/grpc-web", () => {
       });
 
       it("should allow the caller to supply multiple messages", (done) => {
-        const [ reqMsgOne, reqMsgTwo ] = makePayloads("one", "two");
+        const reqMsgOne = new StreamRequest();
+        reqMsgOne.setSomeString("one");
+        const reqMsgTwo = new StreamRequest();
+        reqMsgTwo.setSomeString("two");
         const sentMessageBytes: ArrayBufferView[] = [];
 
         makeClient(new StubTransportBuilder().withMessageListener(v => { sentMessageBytes.push(v); }))