diff --git a/packages/grpc-js/package.json b/packages/grpc-js/package.json
index 53910805..e6e3195e 100644
--- a/packages/grpc-js/package.json
+++ b/packages/grpc-js/package.json
@@ -16,10 +16,10 @@
   "license": "Apache-2.0",
   "devDependencies": {
     "@types/lodash": "^4.14.108",
-    "@types/mocha": "^2.2.43",
-    "@types/node": "^10.5.4",
+    "@types/mocha": "^5.2.6",
+    "@types/node": "^11.13.2",
     "clang-format": "^1.0.55",
-    "gts": "^0.5.1",
+    "gts": "^0.9.0",
     "lodash": "^4.17.4",
     "typescript": "~3.3.3333"
   },
@@ -42,7 +42,7 @@
     "posttest": "npm run check"
   },
   "dependencies": {
-    "semver": "^5.5.0"
+    "semver": "^6.0.0"
   },
   "files": [
     "build/src/*.{js,d.ts}",
diff --git a/packages/grpc-js/src/make-client.ts b/packages/grpc-js/src/make-client.ts
index 244604f7..46d83bce 100644
--- a/packages/grpc-js/src/make-client.ts
+++ b/packages/grpc-js/src/make-client.ts
@@ -19,9 +19,13 @@ import {ChannelCredentials} from './channel-credentials';
 import {ChannelOptions} from './channel-options';
 import {Client} from './client';
 
-export interface Serialize<T> { (value: T): Buffer; }
+export interface Serialize<T> {
+  (value: T): Buffer;
+}
 
-export interface Deserialize<T> { (bytes: Buffer): T; }
+export interface Deserialize<T> {
+  (bytes: Buffer): T;
+}
 
 export interface MethodDefinition<RequestType, ResponseType> {
   path: string;
diff --git a/packages/grpc-js/test/test-call-stream.ts b/packages/grpc-js/test/test-call-stream.ts
index af6ae43a..e2c8ff5c 100644
--- a/packages/grpc-js/test/test-call-stream.ts
+++ b/packages/grpc-js/test/test-call-stream.ts
@@ -64,6 +64,7 @@ class ClientHttp2StreamMock extends stream.Duplex implements
   endAfterHeaders = false;
   pending = false;
   rstCode = 0;
+  readonly bufferSize: number = 0;
   readonly sentHeaders: OutgoingHttpHeaders = {};
   readonly sentInfoHeaders?: OutgoingHttpHeaders[] = [];
   readonly sentTrailers?: OutgoingHttpHeaders = undefined;