diff --git a/src/vs/workbench/services/environment/browser/environmentService.ts b/src/vs/workbench/services/environment/browser/environmentService.ts
index 6760aeda0506c7bb2c4e5d26aa23374eea52ef7d..52d0792082bcfc618df7ede7e9b7add4b95f3d49 100644
--- a/src/vs/workbench/services/environment/browser/environmentService.ts
+++ b/src/vs/workbench/services/environment/browser/environmentService.ts
@@ -276,6 +276,9 @@ export class BrowserWorkbenchEnvironmentService implements IWorkbenchEnvironment
 						extensionHostDebugEnvironment.extensionDevelopmentLocationURI = [URI.parse(value)];
 						extensionHostDebugEnvironment.isExtensionDevelopment = true;
 						break;
+					case 'extensionTestsPath':
+						extensionHostDebugEnvironment.extensionTestsLocationURI = URI.parse(value);
+						break;
 					case 'debugId':
 						extensionHostDebugEnvironment.params.debugId = value;
 						break;