diff --git a/src/vs/workbench/parts/tasks/node/taskConfiguration.ts b/src/vs/workbench/parts/tasks/node/taskConfiguration.ts
index e5279fb2a42..2514a6b01d3 100644
--- a/src/vs/workbench/parts/tasks/node/taskConfiguration.ts
+++ b/src/vs/workbench/parts/tasks/node/taskConfiguration.ts
@@ -637,14 +637,17 @@ namespace ShellConfiguration {
 
 	export function is(value: any): value is ShellConfiguration {
 		let candidate: ShellConfiguration = value;
-		return candidate && (Types.isString(candidate.executable) || (candidate.args === void 0 || Types.isStringArray(candidate.args)));
+		return candidate && (Types.isString(candidate.executable) || Types.isStringArray(candidate.args));
 	}
 
 	export function from(this: void, config: ShellConfiguration, context: ParseContext): Tasks.ShellConfiguration {
 		if (!is(config)) {
 			return undefined;
 		}
-		let result: ShellConfiguration = { executable: config.executable };
+		let result: ShellConfiguration = {};
+		if (config.executable !== void 0) {
+			result.executable = config.executable;
+		}
 		if (config.args !== void 0) {
 			result.args = config.args.slice();
 		}
diff --git a/src/vs/workbench/parts/tasks/test/electron-browser/configuration.test.ts b/src/vs/workbench/parts/tasks/test/electron-browser/configuration.test.ts
index 42f7ca9a6eb..5a20b10de7d 100644
--- a/src/vs/workbench/parts/tasks/test/electron-browser/configuration.test.ts
+++ b/src/vs/workbench/parts/tasks/test/electron-browser/configuration.test.ts
@@ -1324,7 +1324,6 @@ suite('Tasks version 0.1.0', () => {
 		testConfiguration(external, builder);
 	});
 
-	/*
 	test('tasks: with command and args', () => {
 		let external: ExternalTaskRunnerConfiguration = {
 			version: '0.1.0',
@@ -1348,7 +1347,6 @@ suite('Tasks version 0.1.0', () => {
 			runtime(Tasks.RuntimeType.Shell).args(['arg']).options({ cwd: 'cwd', env: { env: 'env' } });
 		testConfiguration(external, builder);
 	});
-	*/
 
 	test('tasks: with command os specific', () => {
 		let name: string = Platform.isWindows ? 'tsc.win' : 'tsc';