diff --git a/src/cssWorker.ts b/src/cssWorker.ts
index 51686a79..f1d2a936 100644
--- a/src/cssWorker.ts
+++ b/src/cssWorker.ts
@@ -4,6 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 'use strict';
 
+import Thenable = monaco.Thenable;
 import Promise = monaco.Promise;
 import IWorkerContext = monaco.worker.IWorkerContext;
 
@@ -41,7 +42,7 @@ export class CSSWorker {
 
 	// --- language service host ---------------
 
-	doValidation(uri: string): Promise<ls.Diagnostic[]> {
+	doValidation(uri: string): Thenable<ls.Diagnostic[]> {
 		let document = this._getTextDocument(uri);
 		if (document) {
 			let stylesheet = this._languageService.parseStylesheet(document);
@@ -50,66 +51,66 @@ export class CSSWorker {
 		}
 		return Promise.as([]);
 	}
-	doComplete(uri: string, position: ls.Position): Promise<ls.CompletionList> {
+	doComplete(uri: string, position: ls.Position): Thenable<ls.CompletionList> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let completions = this._languageService.doComplete(document, position, stylesheet);
 		return Promise.as(completions);
 	}
-	doHover(uri: string, position: ls.Position): Promise<ls.Hover> {
+	doHover(uri: string, position: ls.Position): Thenable<ls.Hover> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let hover = this._languageService.doHover(document, position, stylesheet);
 		return Promise.as(hover);
 	}
-	findDefinition(uri: string, position: ls.Position): Promise<ls.Location> {
+	findDefinition(uri: string, position: ls.Position): Thenable<ls.Location> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let definition = this._languageService.findDefinition(document, position, stylesheet);
 		return Promise.as(definition);
 	}
-	findReferences(uri: string, position: ls.Position): Promise<ls.Location[]> {
+	findReferences(uri: string, position: ls.Position): Thenable<ls.Location[]> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let references = this._languageService.findReferences(document, position, stylesheet);
 		return Promise.as(references);
 	}
-	findDocumentHighlights(uri: string, position: ls.Position): Promise<ls.DocumentHighlight[]> {
+	findDocumentHighlights(uri: string, position: ls.Position): Thenable<ls.DocumentHighlight[]> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let highlights = this._languageService.findDocumentHighlights(document, position, stylesheet);
 		return Promise.as(highlights);
 	}
-	findDocumentSymbols(uri: string): Promise<ls.SymbolInformation[]> {
+	findDocumentSymbols(uri: string): Thenable<ls.SymbolInformation[]> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let symbols = this._languageService.findDocumentSymbols(document, stylesheet);
 		return Promise.as(symbols);
 	}
-	doCodeActions(uri: string, range: ls.Range, context: ls.CodeActionContext): Promise<ls.Command[]> {
+	doCodeActions(uri: string, range: ls.Range, context: ls.CodeActionContext): Thenable<ls.Command[]> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let actions = this._languageService.doCodeActions(document, range, context, stylesheet);
 		return Promise.as(actions);
 	}
-	findDocumentColors(uri: string): Promise<cssService.ColorInformation[]> {
+	findDocumentColors(uri: string): Thenable<ls.ColorInformation[]> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let colorSymbols = this._languageService.findDocumentColors(document, stylesheet);
 		return Promise.as(colorSymbols);
 	}
-	getColorPresentations(uri: string, color: cssService.Color, range: ls.Range): Promise<cssService.ColorPresentation[]> {
+	getColorPresentations(uri: string, color: ls.Color, range: ls.Range): Thenable<ls.ColorPresentation[]> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let colorPresentations = this._languageService.getColorPresentations(document, stylesheet, color, range);
 		return Promise.as(colorPresentations);
 	}
-	provideFoldingRanges(uri: string, context?: { rangeLimit?: number; }): Promise<cssService.FoldingRange[]> {
+	provideFoldingRanges(uri: string, context?: { rangeLimit?: number; }): Thenable<ls.FoldingRange[]> {
 		let document = this._getTextDocument(uri);
 		let ranges = this._languageService.getFoldingRanges(document, context);
 		return Promise.as(ranges);
 	}
-	doRename(uri: string, position: ls.Position, newName: string): Promise<ls.WorkspaceEdit> {
+	doRename(uri: string, position: ls.Position, newName: string): Thenable<ls.WorkspaceEdit> {
 		let document = this._getTextDocument(uri);
 		let stylesheet = this._languageService.parseStylesheet(document);
 		let renames = this._languageService.doRename(document, position, newName, stylesheet);