diff --git a/extensions/npm/src/features/jsonContributions.ts b/extensions/npm/src/features/jsonContributions.ts
index bae32a5c6a9..dcd5411e445 100644
--- a/extensions/npm/src/features/jsonContributions.ts
+++ b/extensions/npm/src/features/jsonContributions.ts
@@ -10,7 +10,7 @@ import { XHRRequest } from 'request-light';
 
 import {
 	CompletionItem, CompletionItemProvider, CompletionList, TextDocument, Position, Hover, HoverProvider,
-	CancellationToken, Range, MarkedString, DocumentSelector, languages, Disposable, Uri
+	CancellationToken, Range, DocumentSelector, languages, Disposable, Uri, MarkdownString
 } from 'vscode';
 
 export interface ISuggestionsCollector {
@@ -22,7 +22,7 @@ export interface ISuggestionsCollector {
 
 export interface IJSONContribution {
 	getDocumentSelector(): DocumentSelector;
-	getInfoContribution(resourceUri: Uri, location: Location): Thenable<MarkedString[] | null> | null;
+	getInfoContribution(resourceUri: Uri, location: Location): Thenable<MarkdownString[] | null> | null;
 	collectPropertySuggestions(resourceUri: Uri, location: Location, currentWord: string, addValue: boolean, isLast: boolean, result: ISuggestionsCollector): Thenable<any> | null;
 	collectValueSuggestions(resourceUri: Uri, location: Location, result: ISuggestionsCollector): Thenable<any> | null;
 	collectDefaultSuggestions(resourceUri: Uri, result: ISuggestionsCollector): Thenable<any>;
diff --git a/extensions/npm/src/features/packageJSONContribution.ts b/extensions/npm/src/features/packageJSONContribution.ts
index 3afbf98259b..c1bd6fd4c93 100644
--- a/extensions/npm/src/features/packageJSONContribution.ts
+++ b/extensions/npm/src/features/packageJSONContribution.ts
@@ -3,7 +3,7 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import { MarkedString, CompletionItemKind, CompletionItem, DocumentSelector, SnippetString, workspace, MarkdownString, Uri } from 'vscode';
+import { CompletionItemKind, CompletionItem, DocumentSelector, SnippetString, workspace, MarkdownString, Uri } from 'vscode';
 import { IJSONContribution, ISuggestionsCollector } from './jsonContributions';
 import { XHRRequest } from 'request-light';
 import { Location } from 'jsonc-parser';
@@ -320,7 +320,7 @@ export class PackageJSONContribution implements IJSONContribution {
 		return undefined;
 	}
 
-	public getInfoContribution(resource: Uri, location: Location): Thenable<MarkedString[] | null> | null {
+	public getInfoContribution(resource: Uri, location: Location): Thenable<MarkdownString[] | null> | null {
 		if (!this.isEnabled()) {
 			return null;
 		}
diff --git a/extensions/typescript-language-features/src/languageFeatures/hover.ts b/extensions/typescript-language-features/src/languageFeatures/hover.ts
index 36f39971ecd..62113e8ce31 100644
--- a/extensions/typescript-language-features/src/languageFeatures/hover.ts
+++ b/extensions/typescript-language-features/src/languageFeatures/hover.ts
@@ -52,7 +52,7 @@ class TypeScriptHoverProvider implements vscode.HoverProvider {
 		data: Proto.QuickInfoResponseBody,
 		source: ServerType | undefined,
 	) {
-		const parts: vscode.MarkedString[] = [];
+		const parts: vscode.MarkdownString[] = [];
 
 		if (data.displayString) {
 			const displayParts: string[] = [];
@@ -66,8 +66,7 @@ class TypeScriptHoverProvider implements vscode.HoverProvider {
 			}
 
 			displayParts.push(data.displayString);
-
-			parts.push({ language: 'typescript', value: displayParts.join(' ') });
+			parts.push(new vscode.MarkdownString().appendCodeblock(displayParts.join(' '), 'typescript'));
 		}
 		parts.push(markdownDocumentation(data.documentation, data.tags, this.client));
 		return parts;
diff --git a/src/vs/vscode.d.ts b/src/vs/vscode.d.ts
index d48c4fce858..7064bbcd593 100644
--- a/src/vs/vscode.d.ts
+++ b/src/vs/vscode.d.ts
@@ -1055,7 +1055,7 @@ declare module 'vscode' {
 		/**
 		 * A message that should be rendered when hovering over the decoration.
 		 */
-		hoverMessage?: MarkedString | MarkedString[];
+		hoverMessage?: MarkdownString | (MarkdownString | MarkedString)[] | MarkedString;
 
 		/**
 		 * Render options applied to the current decoration. For performance reasons, keep the
@@ -2625,7 +2625,7 @@ declare module 'vscode' {
 	 *
 	 * @deprecated This type is deprecated, please use {@link MarkdownString `MarkdownString`} instead.
 	 */
-	export type MarkedString = MarkdownString | string | { language: string; value: string };
+	export type MarkedString = string | { language: string; value: string };
 
 	/**
 	 * A hover represents additional information for a symbol or word. Hovers are
@@ -2636,7 +2636,7 @@ declare module 'vscode' {
 		/**
 		 * The contents of this hover.
 		 */
-		contents: MarkedString[];
+		contents: (MarkdownString | MarkedString)[];
 
 		/**
 		 * The range to which this hover applies. When missing, the
@@ -2651,7 +2651,7 @@ declare module 'vscode' {
 		 * @param contents The contents of the hover.
 		 * @param range The range to which the hover applies.
 		 */
-		constructor(contents: MarkedString | MarkedString[], range?: Range);
+		constructor(contents: MarkdownString | (MarkdownString | MarkedString)[] | MarkedString, range?: Range);
 	}
 
 	/**
diff --git a/src/vs/workbench/api/common/extHostTypes.ts b/src/vs/workbench/api/common/extHostTypes.ts
index 21bb3cbb6d7..54ba8c1e240 100644
--- a/src/vs/workbench/api/common/extHostTypes.ts
+++ b/src/vs/workbench/api/common/extHostTypes.ts
@@ -6,7 +6,7 @@
 import { asArray, coalesceInPlace, equals } from 'vs/base/common/arrays';
 import { illegalArgument } from 'vs/base/common/errors';
 import { IRelativePattern } from 'vs/base/common/glob';
-import { isMarkdownString, MarkdownString as BaseMarkdownString } from 'vs/base/common/htmlContent';
+import { MarkdownString as BaseMarkdownString } from 'vs/base/common/htmlContent';
 import { ReadonlyMapView, ResourceMap } from 'vs/base/common/map';
 import { Mimes, normalizeMimeType } from 'vs/base/common/mime';
 import { isArray, isStringArray } from 'vs/base/common/types';
@@ -997,20 +997,18 @@ export class Diagnostic {
 @es5ClassCompat
 export class Hover {
 
-	public contents: vscode.MarkdownString[] | vscode.MarkedString[];
+	public contents: (vscode.MarkdownString | vscode.MarkedString)[];
 	public range: Range | undefined;
 
 	constructor(
-		contents: vscode.MarkdownString | vscode.MarkedString | vscode.MarkdownString[] | vscode.MarkedString[],
+		contents: vscode.MarkdownString | vscode.MarkedString | (vscode.MarkdownString | vscode.MarkedString)[],
 		range?: Range
 	) {
 		if (!contents) {
 			throw new Error('Illegal argument, contents must be defined');
 		}
 		if (Array.isArray(contents)) {
-			this.contents = <vscode.MarkdownString[] | vscode.MarkedString[]>contents;
-		} else if (isMarkdownString(contents)) {
-			this.contents = [contents];
+			this.contents = contents;
 		} else {
 			this.contents = [contents];
 		}