diff --git a/src/vs/workbench/api/node/extHost.api.impl.ts b/src/vs/workbench/api/node/extHost.api.impl.ts
index dd52d40145b4b4b7d0a4503c5b083cb1acf268a5..02fe0073cfedd34c14027bb406b5db880f157f68 100644
--- a/src/vs/workbench/api/node/extHost.api.impl.ts
+++ b/src/vs/workbench/api/node/extHost.api.impl.ts
@@ -111,7 +111,7 @@ export function createApiFactory(
 	const extHostDebugService = rpcProtocol.set(ExtHostContext.ExtHostDebugService, new ExtHostDebugService(rpcProtocol, extHostWorkspace, extensionService));
 	rpcProtocol.set(ExtHostContext.ExtHostConfiguration, extHostConfiguration);
 	const extHostDiagnostics = rpcProtocol.set(ExtHostContext.ExtHostDiagnostics, new ExtHostDiagnostics(rpcProtocol));
-	const extHostLanguageFeatures = rpcProtocol.set(ExtHostContext.ExtHostLanguageFeatures, new ExtHostLanguageFeatures(rpcProtocol, extHostDocuments, extHostCommands, extHostHeapService, extHostDiagnostics));
+	const extHostLanguageFeatures = rpcProtocol.set(ExtHostContext.ExtHostLanguageFeatures, new ExtHostLanguageFeatures(rpcProtocol, null, extHostDocuments, extHostCommands, extHostHeapService, extHostDiagnostics));
 	const extHostFileSystem = rpcProtocol.set(ExtHostContext.ExtHostFileSystem, new ExtHostFileSystem(rpcProtocol, extHostLanguageFeatures));
 	const extHostFileSystemEvent = rpcProtocol.set(ExtHostContext.ExtHostFileSystemEventService, new ExtHostFileSystemEventService());
 	const extHostQuickOpen = rpcProtocol.set(ExtHostContext.ExtHostQuickOpen, new ExtHostQuickOpen(rpcProtocol, extHostWorkspace, extHostCommands));
diff --git a/src/vs/workbench/api/node/extHostLanguageFeatures.ts b/src/vs/workbench/api/node/extHostLanguageFeatures.ts
index 5e99422f862403ee8b94653e4ce5089187b2e9db..8e0753d3df4b8ed948d5560feef111b4e30dc79d 100644
--- a/src/vs/workbench/api/node/extHostLanguageFeatures.ts
+++ b/src/vs/workbench/api/node/extHostLanguageFeatures.ts
@@ -837,10 +837,15 @@ type Adapter = OutlineAdapter | CodeLensAdapter | DefinitionAdapter | HoverAdapt
 	| SuggestAdapter | SignatureHelpAdapter | LinkProviderAdapter | ImplementationAdapter | TypeDefinitionAdapter
 	| ColorProviderAdapter | FoldingProviderAdapter;
 
+export interface ISchemeTransformer {
+	transformOutgoing(scheme: string): string;
+}
+
 export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 
 	private static _handlePool: number = 0;
 
+	private readonly _schemeTransformer: ISchemeTransformer;
 	private _proxy: MainThreadLanguageFeaturesShape;
 	private _documents: ExtHostDocuments;
 	private _commands: ExtHostCommands;
@@ -850,11 +855,13 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 
 	constructor(
 		mainContext: IMainContext,
+		schemeTransformer: ISchemeTransformer,
 		documents: ExtHostDocuments,
 		commands: ExtHostCommands,
 		heapMonitor: ExtHostHeapService,
 		diagnostics: ExtHostDiagnostics
 	) {
+		this._schemeTransformer = schemeTransformer;
 		this._proxy = mainContext.getProxy(MainContext.MainThreadLanguageFeatures);
 		this._documents = documents;
 		this._commands = commands;
@@ -891,6 +898,9 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 	}
 
 	private _transformScheme(scheme: string): string {
+		if (this._schemeTransformer && typeof scheme === 'string') {
+			return this._schemeTransformer.transformOutgoing(scheme);
+		}
 		return scheme;
 	}
 
diff --git a/src/vs/workbench/test/electron-browser/api/extHostApiCommands.test.ts b/src/vs/workbench/test/electron-browser/api/extHostApiCommands.test.ts
index db8e34b495b77711bd273b08cc8c8987f8752c2e..b024891dc842a40b563caa7c043bae5a69e1bdd2 100644
--- a/src/vs/workbench/test/electron-browser/api/extHostApiCommands.test.ts
+++ b/src/vs/workbench/test/electron-browser/api/extHostApiCommands.test.ts
@@ -129,7 +129,7 @@ suite('ExtHostLanguageFeatureCommands', function () {
 		const diagnostics = new ExtHostDiagnostics(rpcProtocol);
 		rpcProtocol.set(ExtHostContext.ExtHostDiagnostics, diagnostics);
 
-		extHost = new ExtHostLanguageFeatures(rpcProtocol, extHostDocuments, commands, heapService, diagnostics);
+		extHost = new ExtHostLanguageFeatures(rpcProtocol, null, extHostDocuments, commands, heapService, diagnostics);
 		rpcProtocol.set(ExtHostContext.ExtHostLanguageFeatures, extHost);
 
 		mainThread = rpcProtocol.set(MainContext.MainThreadLanguageFeatures, inst.createInstance(MainThreadLanguageFeatures, rpcProtocol));
diff --git a/src/vs/workbench/test/electron-browser/api/extHostLanguageFeatures.test.ts b/src/vs/workbench/test/electron-browser/api/extHostLanguageFeatures.test.ts
index 511e5e963e58155b33c2e31bc180a59007e352cd..f0748586c5d6c0b5a03ef531df7b4fa7de740f3f 100644
--- a/src/vs/workbench/test/electron-browser/api/extHostLanguageFeatures.test.ts
+++ b/src/vs/workbench/test/electron-browser/api/extHostLanguageFeatures.test.ts
@@ -111,7 +111,7 @@ suite('ExtHostLanguageFeatures', function () {
 		const diagnostics = new ExtHostDiagnostics(rpcProtocol);
 		rpcProtocol.set(ExtHostContext.ExtHostDiagnostics, diagnostics);
 
-		extHost = new ExtHostLanguageFeatures(rpcProtocol, extHostDocuments, commands, heapService, diagnostics);
+		extHost = new ExtHostLanguageFeatures(rpcProtocol, null, extHostDocuments, commands, heapService, diagnostics);
 		rpcProtocol.set(ExtHostContext.ExtHostLanguageFeatures, extHost);
 
 		mainThread = rpcProtocol.set(MainContext.MainThreadLanguageFeatures, inst.createInstance(MainThreadLanguageFeatures, rpcProtocol));