diff --git a/src/vs/base/node/pfs.ts b/src/vs/base/node/pfs.ts
index b6a07756381..6cf71160c50 100644
--- a/src/vs/base/node/pfs.ts
+++ b/src/vs/base/node/pfs.ts
@@ -360,7 +360,7 @@ function doWriteFileAndFlush(path: string, data: string | Buffer | Uint8Array, o
 			}
 
 			// Flush contents (not metadata) of the file to disk
-			fs.fdatasync(fd, (syncError: Error) => {
+			fs.fdatasync(fd, (syncError: Error | null) => {
 
 				// In some exotic setups it is well possible that node fails to sync
 				// In that case we disable flushing and warn to the console
diff --git a/src/vs/base/node/processes.ts b/src/vs/base/node/processes.ts
index b6f7742e2b3..1fb6c3c2354 100644
--- a/src/vs/base/node/processes.ts
+++ b/src/vs/base/node/processes.ts
@@ -409,7 +409,7 @@ export function createQueuedSender(childProcess: cp.ChildProcess): IQueuedSender
 			return;
 		}
 
-		const result = childProcess.send(msg, (error: Error) => {
+		const result = childProcess.send(msg, (error: Error | null) => {
 			if (error) {
 				console.error(error); // unlikely to happen, best we can do is log this error
 			}
diff --git a/src/vs/code/electron-browser/issue/issueReporterMain.ts b/src/vs/code/electron-browser/issue/issueReporterMain.ts
index 6b1bab2128b..f47161fb8bf 100644
--- a/src/vs/code/electron-browser/issue/issueReporterMain.ts
+++ b/src/vs/code/electron-browser/issue/issueReporterMain.ts
@@ -440,7 +440,7 @@ export class IssueReporter extends Disposable {
 			sendWorkbenchCommand('workbench.action.reloadWindowWithExtensionsDisabled');
 		});
 
-		this.addEventListener('extensionBugsLink', 'click', (e: MouseEvent) => {
+		this.addEventListener('extensionBugsLink', 'click', (e: Event) => {
 			const url = (<HTMLElement>e.target).innerText;
 			shell.openExternal(url);
 		});
diff --git a/src/vs/editor/contrib/gotoError/gotoError.ts b/src/vs/editor/contrib/gotoError/gotoError.ts
index 304f06cf306..0de7e22fdb5 100644
--- a/src/vs/editor/contrib/gotoError/gotoError.ts
+++ b/src/vs/editor/contrib/gotoError/gotoError.ts
@@ -304,7 +304,7 @@ export class MarkerController implements IEditorContribution {
 		model.currentMarker = marker;
 	}
 
-	private _onMarkerChanged(changedResources: URI[]): void {
+	private _onMarkerChanged(changedResources: readonly URI[]): void {
 		const editorModel = this._editor.getModel();
 		if (!editorModel) {
 			return;
diff --git a/src/vs/workbench/browser/parts/editor/breadcrumbsPicker.ts b/src/vs/workbench/browser/parts/editor/breadcrumbsPicker.ts
index 276ea0efd8e..022b7645126 100644
--- a/src/vs/workbench/browser/parts/editor/breadcrumbsPicker.ts
+++ b/src/vs/workbench/browser/parts/editor/breadcrumbsPicker.ts
@@ -17,7 +17,7 @@ import 'vs/css!./media/breadcrumbscontrol';
 import { OutlineElement, OutlineModel, TreeElement } from 'vs/editor/contrib/documentSymbols/outlineModel';
 import { IConfigurationService, IConfigurationOverrides } from 'vs/platform/configuration/common/configuration';
 import { FileKind, IFileService, IFileStat } from 'vs/platform/files/common/files';
-import { IConstructorSignature1, IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
+import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
 import { WorkbenchDataTree, WorkbenchAsyncDataTree } from 'vs/platform/list/browser/listService';
 import { breadcrumbsPickerBackground, widgetShadow } from 'vs/platform/theme/common/colorRegistry';
 import { IWorkspace, IWorkspaceContextService, IWorkspaceFolder } from 'vs/platform/workspace/common/workspace';
@@ -30,11 +30,9 @@ import { OutlineVirtualDelegate, OutlineGroupRenderer, OutlineElementRenderer, O
 import { IIdentityProvider, IListVirtualDelegate, IKeyboardNavigationLabelProvider } from 'vs/base/browser/ui/list/list';
 
 export function createBreadcrumbsPicker(instantiationService: IInstantiationService, parent: HTMLElement, element: BreadcrumbElement): BreadcrumbsPicker {
-	const ctor: IConstructorSignature1<HTMLElement, BreadcrumbsPicker> = element instanceof FileElement
-		? BreadcrumbsFilePicker
-		: BreadcrumbsOutlinePicker;
-
-	return instantiationService.createInstance(ctor, parent);
+	return element instanceof FileElement
+		? instantiationService.createInstance(BreadcrumbsFilePicker, parent)
+		: instantiationService.createInstance(BreadcrumbsOutlinePicker, parent);
 }
 
 interface ILayoutInfo {
diff --git a/src/vs/workbench/contrib/markdown/common/markdownDocumentRenderer.ts b/src/vs/workbench/contrib/markdown/common/markdownDocumentRenderer.ts
index e2b23f76745..1cafaebd93e 100644
--- a/src/vs/workbench/contrib/markdown/common/markdownDocumentRenderer.ts
+++ b/src/vs/workbench/contrib/markdown/common/markdownDocumentRenderer.ts
@@ -33,7 +33,7 @@ async function getRenderer(
 	renderer.code = (_code, lang) => {
 		const modeId = modeService.getModeIdForLanguageName(lang);
 		if (modeId) {
-			result.push(extensionService.whenInstalledExtensionsRegistered().then<ITokenizationSupport | null>(() => {
+			result.push(extensionService.whenInstalledExtensionsRegistered().then((): PromiseLike<ITokenizationSupport> | null => {
 				modeService.triggerMode(modeId);
 				return TokenizationRegistry.getPromise(modeId);
 			}));