diff --git a/src/vs/workbench/api/node/extHostConfiguration.ts b/src/vs/workbench/api/node/extHostConfiguration.ts
index 93b2d217d8e..0b4830a4c8a 100644
--- a/src/vs/workbench/api/node/extHostConfiguration.ts
+++ b/src/vs/workbench/api/node/extHostConfiguration.ts
@@ -107,12 +107,16 @@ export class ExtHostConfiguration implements ExtHostConfigurationShape {
 						return isObject(target) ?
 							new Proxy(target, {
 								get: (target: any, property: string) => {
+									if (typeof property === 'string' && property.toLowerCase() === 'tojson') {
+										cloneTarget();
+										return () => clonedTarget;
+									}
 									if (clonedConfig) {
 										clonedTarget = clonedTarget ? clonedTarget : lookUp(clonedConfig, accessor);
 										return clonedTarget[property];
 									}
 									const result = target[property];
-									if (typeof property === 'string' && property.toLowerCase() !== 'tojson') {
+									if (typeof property === 'string') {
 										return cloneOnWriteProxy(result, `${accessor}.${property}`);
 									}
 									return result;
diff --git a/src/vs/workbench/test/electron-browser/api/extHostConfiguration.test.ts b/src/vs/workbench/test/electron-browser/api/extHostConfiguration.test.ts
index 382cbc08b75..4aae41a952d 100644
--- a/src/vs/workbench/test/electron-browser/api/extHostConfiguration.test.ts
+++ b/src/vs/workbench/test/electron-browser/api/extHostConfiguration.test.ts
@@ -17,6 +17,7 @@ import { mock } from 'vs/workbench/test/electron-browser/api/mock';
 import { IWorkspaceFolder, WorkspaceFolder } from 'vs/platform/workspace/common/workspace';
 import { ConfigurationTarget } from 'vs/platform/configuration/common/configuration';
 import { NullLogService } from 'vs/platform/log/common/log';
+import { assign } from 'vs/base/common/objects';
 
 suite('ExtHostConfiguration', function () {
 
@@ -146,6 +147,88 @@ suite('ExtHostConfiguration', function () {
 		assert.equal(actual['statusBar.foreground'], 'somevalue');
 	});
 
+	test('Stringify returned configuration', function () {
+
+		const all = createExtHostConfiguration({
+			'farboo': {
+				'config0': true,
+				'nested': {
+					'config1': 42,
+					'config2': 'Das Pferd frisst kein Reis.'
+				},
+				'config4': ''
+			},
+			'workbench': {
+				'colorCustomizations': {
+					'statusBar.foreground': 'somevalue'
+				},
+				'emptyobjectkey': {
+				}
+			}
+		});
+
+		let testObject = all.getConfiguration();
+		let actual = testObject.get('farboo');
+		assert.deepEqual(JSON.stringify({
+			'config0': true,
+			'nested': {
+				'config1': 42,
+				'config2': 'Das Pferd frisst kein Reis.'
+			},
+			'config4': ''
+		}), JSON.stringify(actual));
+
+		assert.deepEqual(undefined, JSON.stringify(testObject.get('unknownkey')));
+
+		actual = testObject.get('farboo');
+		actual['config0'] = false;
+		assert.deepEqual(JSON.stringify({
+			'config0': false,
+			'nested': {
+				'config1': 42,
+				'config2': 'Das Pferd frisst kein Reis.'
+			},
+			'config4': ''
+		}), JSON.stringify(actual));
+
+		actual = testObject.get('workbench')['colorCustomizations'];
+		actual['statusBar.background'] = 'anothervalue';
+		assert.deepEqual(JSON.stringify({
+			'statusBar.foreground': 'somevalue',
+			'statusBar.background': 'anothervalue'
+		}), JSON.stringify(actual));
+
+		actual = testObject.get('workbench');
+		actual['unknownkey'] = 'somevalue';
+		assert.deepEqual(JSON.stringify({
+			'colorCustomizations': {
+				'statusBar.foreground': 'somevalue'
+			},
+			'emptyobjectkey': {},
+			'unknownkey': 'somevalue'
+		}), JSON.stringify(actual));
+
+		actual = all.getConfiguration('workbench').get('emptyobjectkey');
+		actual = assign(actual || {}, {
+			'statusBar.background': `#0ff`,
+			'statusBar.foreground': `#ff0`,
+		});
+		assert.deepEqual(JSON.stringify({
+			'statusBar.background': `#0ff`,
+			'statusBar.foreground': `#ff0`,
+		}), JSON.stringify(actual));
+
+		actual = all.getConfiguration('workbench').get('unknownkey');
+		actual = assign(actual || {}, {
+			'statusBar.background': `#0ff`,
+			'statusBar.foreground': `#ff0`,
+		});
+		assert.deepEqual(JSON.stringify({
+			'statusBar.background': `#0ff`,
+			'statusBar.foreground': `#ff0`,
+		}), JSON.stringify(actual));
+	});
+
 	test('cannot modify returned configuration', function () {
 
 		const all = createExtHostConfiguration({