diff --git a/src/vs/workbench/services/preferences/common/preferencesValidation.ts b/src/vs/workbench/services/preferences/common/preferencesValidation.ts
index 67152d0889b..b722a3cee43 100644
--- a/src/vs/workbench/services/preferences/common/preferencesValidation.ts
+++ b/src/vs/workbench/services/preferences/common/preferencesValidation.ts
@@ -6,7 +6,7 @@
 import * as nls from 'vs/nls';
 import { JSONSchemaType } from 'vs/base/common/jsonSchema';
 import { Color } from 'vs/base/common/color';
-import { isArray, isObject, isUndefinedOrNull, isString, isStringArray, isNumber } from 'vs/base/common/types';
+import { isArray, isObject, isUndefinedOrNull, isString, isStringArray } from 'vs/base/common/types';
 import { IConfigurationPropertySchema } from 'vs/platform/configuration/common/configurationRegistry';
 
 type Validator<T> = { enabled: boolean, isValid: (value: T) => boolean; message: string };