diff --git a/build/package.json b/build/package.json
index 4ed899ed408..e655065889e 100644
--- a/build/package.json
+++ b/build/package.json
@@ -61,7 +61,7 @@
     "plist": "^3.0.1",
     "source-map": "0.6.1",
     "tmp": "^0.2.1",
-    "typescript": "^4.5.0-dev.20210810",
+    "typescript": "^4.5.0-dev.20210817",
     "vsce": "1.48.0",
     "vscode-universal-bundler": "^0.0.2"
   },
diff --git a/build/yarn.lock b/build/yarn.lock
index 6ab76305982..e0d34a5e444 100644
--- a/build/yarn.lock
+++ b/build/yarn.lock
@@ -2348,10 +2348,10 @@ typed-rest-client@^0.9.0:
     tunnel "0.0.4"
     underscore "1.8.3"
 
-typescript@^4.5.0-dev.20210810:
-  version "4.5.0-dev.20210810"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.5.0-dev.20210810.tgz#e29c56a180a3ea43dca880000f8b1cbb4da5af48"
-  integrity sha512-9d8OrY8J3LbkWgjrPLE8pXOI4Z8bfS9N2SudgvrZOgYUmEODJYfA+MIZ6Zv/qrVSRH3M5632/0CjJr0Zk/sqWA==
+typescript@^4.5.0-dev.20210817:
+  version "4.5.0-dev.20210817"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.5.0-dev.20210817.tgz#6b0d0ce68c2381cc85fd0d609817cb3576eb9480"
+  integrity sha512-G427tdOZrQKSEUcLF+dq57gK7D6CzxhbZggpEwqZP1HDuBhIk2bu+br9QvR5uoubR2P6lHhWhUZaCDmkIpnnDQ==
 
 uc.micro@^1.0.1, uc.micro@^1.0.5:
   version "1.0.5"
diff --git a/package.json b/package.json
index dd5907f4cce..1374bb0af67 100644
--- a/package.json
+++ b/package.json
@@ -198,7 +198,7 @@
     "style-loader": "^1.0.0",
     "ts-loader": "^9.2.3",
     "tsec": "0.1.4",
-    "typescript": "^4.5.0-dev.20210810",
+    "typescript": "^4.5.0-dev.20210817",
     "typescript-formatter": "7.1.0",
     "underscore": "^1.12.1",
     "util": "^0.12.4",
diff --git a/src/vs/workbench/test/browser/api/extHostWorkspace.test.ts b/src/vs/workbench/test/browser/api/extHostWorkspace.test.ts
index 86fa0e31d1d..37bfb0b6870 100644
--- a/src/vs/workbench/test/browser/api/extHostWorkspace.test.ts
+++ b/src/vs/workbench/test/browser/api/extHostWorkspace.test.ts
@@ -27,7 +27,7 @@ import { FileSystemProviderCapabilities } from 'vs/platform/files/common/files';
 function createExtHostWorkspace(mainContext: IMainContext, data: IWorkspaceData, logService: ILogService): ExtHostWorkspace {
 	const result = new ExtHostWorkspace(
 		new ExtHostRpcService(mainContext),
-		new class extends mock<IExtHostInitDataService>() { workspace = data; },
+		new class extends mock<IExtHostInitDataService>() { override workspace = data; },
 		new class extends mock<IExtHostFileSystemInfo>() { override getCapabilities() { return isLinux ? FileSystemProviderCapabilities.PathCaseSensitive : undefined; } },
 		logService,
 	);
diff --git a/src/vs/workbench/test/electron-browser/api/extHostSearch.test.ts b/src/vs/workbench/test/electron-browser/api/extHostSearch.test.ts
index 97e9723d40e..c5e6b2db736 100644
--- a/src/vs/workbench/test/electron-browser/api/extHostSearch.test.ts
+++ b/src/vs/workbench/test/electron-browser/api/extHostSearch.test.ts
@@ -141,7 +141,7 @@ suite('ExtHostSearch', () => {
 			constructor() {
 				super(
 					rpcProtocol,
-					new class extends mock<IExtHostInitDataService>() { remote = { isRemote: false, authority: undefined, connectionData: null }; },
+					new class extends mock<IExtHostInitDataService>() { override remote = { isRemote: false, authority: undefined, connectionData: null }; },
 					new URITransformerService(null),
 					logService
 				);
diff --git a/yarn.lock b/yarn.lock
index ab3f29f93bd..80babfe5729 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -10236,10 +10236,10 @@ typescript@^2.6.2:
   resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.6.2.tgz#3c5b6fd7f6de0914269027f03c0946758f7673a4"
   integrity sha1-PFtv1/beCRQmkCfwPAlGdY92c6Q=
 
-typescript@^4.5.0-dev.20210810:
-  version "4.5.0-dev.20210810"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.5.0-dev.20210810.tgz#e29c56a180a3ea43dca880000f8b1cbb4da5af48"
-  integrity sha512-9d8OrY8J3LbkWgjrPLE8pXOI4Z8bfS9N2SudgvrZOgYUmEODJYfA+MIZ6Zv/qrVSRH3M5632/0CjJr0Zk/sqWA==
+typescript@^4.5.0-dev.20210817:
+  version "4.5.0-dev.20210817"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.5.0-dev.20210817.tgz#6b0d0ce68c2381cc85fd0d609817cb3576eb9480"
+  integrity sha512-G427tdOZrQKSEUcLF+dq57gK7D6CzxhbZggpEwqZP1HDuBhIk2bu+br9QvR5uoubR2P6lHhWhUZaCDmkIpnnDQ==
 
 typical@^4.0.0:
   version "4.0.0"