diff --git a/src/tsconfig.strictNullChecks.json b/src/tsconfig.strictNullChecks.json
index 5a9778018f9..32867a775ba 100644
--- a/src/tsconfig.strictNullChecks.json
+++ b/src/tsconfig.strictNullChecks.json
@@ -132,6 +132,7 @@
 		"./vs/editor/common/modes/languageConfigurationRegistry.ts",
 		"./vs/editor/common/modes/languageFeatureRegistry.ts",
 		"./vs/editor/common/modes/languageSelector.ts",
+		"./vs/editor/common/modes/linkComputer.ts",
 		"./vs/editor/common/modes/nullMode.ts",
 		"./vs/editor/common/modes/supports.ts",
 		"./vs/editor/common/modes/supports/characterPair.ts",
diff --git a/src/vs/editor/browser/view/viewOutgoingEvents.ts b/src/vs/editor/browser/view/viewOutgoingEvents.ts
index 64677c2485e..8a337c11bb4 100644
--- a/src/vs/editor/browser/view/viewOutgoingEvents.ts
+++ b/src/vs/editor/browser/view/viewOutgoingEvents.ts
@@ -19,18 +19,18 @@ export interface EventCallback<T> {
 
 export class ViewOutgoingEvents extends Disposable {
 
-	public onDidScroll: EventCallback<IScrollEvent> = null;
-	public onDidGainFocus: EventCallback<void> = null;
-	public onDidLoseFocus: EventCallback<void> = null;
-	public onKeyDown: EventCallback<IKeyboardEvent> = null;
-	public onKeyUp: EventCallback<IKeyboardEvent> = null;
-	public onContextMenu: EventCallback<IEditorMouseEvent> = null;
-	public onMouseMove: EventCallback<IEditorMouseEvent> = null;
-	public onMouseLeave: EventCallback<IEditorMouseEvent> = null;
-	public onMouseUp: EventCallback<IEditorMouseEvent> = null;
-	public onMouseDown: EventCallback<IEditorMouseEvent> = null;
-	public onMouseDrag: EventCallback<IEditorMouseEvent> = null;
-	public onMouseDrop: EventCallback<IEditorMouseEvent> = null;
+	public onDidScroll: EventCallback<IScrollEvent> | null = null;
+	public onDidGainFocus: EventCallback<void> | null = null;
+	public onDidLoseFocus: EventCallback<void> | null = null;
+	public onKeyDown: EventCallback<IKeyboardEvent> | null = null;
+	public onKeyUp: EventCallback<IKeyboardEvent> | null = null;
+	public onContextMenu: EventCallback<IEditorMouseEvent> | null = null;
+	public onMouseMove: EventCallback<IEditorMouseEvent> | null = null;
+	public onMouseLeave: EventCallback<IEditorMouseEvent> | null = null;
+	public onMouseUp: EventCallback<IEditorMouseEvent> | null = null;
+	public onMouseDown: EventCallback<IEditorMouseEvent> | null = null;
+	public onMouseDrag: EventCallback<IEditorMouseEvent> | null = null;
+	public onMouseDrop: EventCallback<IEditorMouseEvent> | null = null;
 
 	private _viewModel: IViewModel;
 
diff --git a/src/vs/editor/common/modes/linkComputer.ts b/src/vs/editor/common/modes/linkComputer.ts
index b7f8b2d29b0..dbf78a728d0 100644
--- a/src/vs/editor/common/modes/linkComputer.ts
+++ b/src/vs/editor/common/modes/linkComputer.ts
@@ -123,7 +123,7 @@ const enum CharacterClass {
 	CannotEndIn = 2
 }
 
-let _classifier: CharacterClassifier<CharacterClass> = null;
+let _classifier: CharacterClassifier<CharacterClass> | null = null;
 function getClassifier(): CharacterClassifier<CharacterClass> {
 	if (_classifier === null) {
 		_classifier = new CharacterClassifier<CharacterClass>(CharacterClass.None);
diff --git a/src/vs/editor/standalone/test/browser/standaloneLanguages.test.ts b/src/vs/editor/standalone/test/browser/standaloneLanguages.test.ts
index f2e4e6f3754..e8b3ec85b60 100644
--- a/src/vs/editor/standalone/test/browser/standaloneLanguages.test.ts
+++ b/src/vs/editor/standalone/test/browser/standaloneLanguages.test.ts
@@ -56,7 +56,7 @@ suite('TokenizationSupport2Adapter', () => {
 				}
 			};
 		}
-		public readonly onThemeChange: Event<ITheme> = null;
+		public readonly onThemeChange: Event<ITheme> | null = null;
 	}
 
 	class MockState implements IState {
diff --git a/src/vs/workbench/parts/debug/node/terminals.ts b/src/vs/workbench/parts/debug/node/terminals.ts
index 854e25cbb5d..e6c648cff7b 100644
--- a/src/vs/workbench/parts/debug/node/terminals.ts
+++ b/src/vs/workbench/parts/debug/node/terminals.ts
@@ -29,7 +29,7 @@ export function getTerminalLauncher() {
 	return terminalLauncher;
 }
 
-let _DEFAULT_TERMINAL_LINUX_READY: TPromise<string> = null;
+let _DEFAULT_TERMINAL_LINUX_READY: TPromise<string> | null = null;
 export function getDefaultTerminalLinuxReady(): TPromise<string> {
 	if (!_DEFAULT_TERMINAL_LINUX_READY) {
 		_DEFAULT_TERMINAL_LINUX_READY = new Promise<string>(c => {
diff --git a/src/vs/workbench/parts/emmet/electron-browser/emmetActions.ts b/src/vs/workbench/parts/emmet/electron-browser/emmetActions.ts
index b1a2371edca..b64af96857f 100644
--- a/src/vs/workbench/parts/emmet/electron-browser/emmetActions.ts
+++ b/src/vs/workbench/parts/emmet/electron-browser/emmetActions.ts
@@ -65,7 +65,7 @@ export abstract class EmmetEditorAction extends EditorAction {
 
 	private static readonly emmetSupportedModes = ['html', 'css', 'xml', 'xsl', 'haml', 'jade', 'jsx', 'slim', 'scss', 'sass', 'less', 'stylus', 'styl', 'svg'];
 
-	private _lastGrammarContributions: TPromise<GrammarContributions> = null;
+	private _lastGrammarContributions: TPromise<GrammarContributions> | null = null;
 	private _lastExtensionService: IExtensionService | null = null;
 	private _withGrammarContributions(extensionService: IExtensionService): TPromise<GrammarContributions> {
 		if (this._lastExtensionService !== extensionService) {
diff --git a/src/vs/workbench/parts/execution/electron-browser/terminal.ts b/src/vs/workbench/parts/execution/electron-browser/terminal.ts
index a1dd21b7260..f08fd641f0a 100644
--- a/src/vs/workbench/parts/execution/electron-browser/terminal.ts
+++ b/src/vs/workbench/parts/execution/electron-browser/terminal.ts
@@ -6,7 +6,7 @@
 import * as env from 'vs/base/common/platform';
 import * as pfs from 'vs/base/node/pfs';
 
-let _DEFAULT_TERMINAL_LINUX_READY: Promise<string> = null;
+let _DEFAULT_TERMINAL_LINUX_READY: Promise<string> | null = null;
 export function getDefaultTerminalLinuxReady(): Promise<string> {
 	if (!_DEFAULT_TERMINAL_LINUX_READY) {
 		_DEFAULT_TERMINAL_LINUX_READY = new Promise<string>(c => {