diff --git a/src/vs/workbench/electron-sandbox/desktop.contribution.ts b/src/vs/workbench/electron-sandbox/desktop.contribution.ts
index fa7f55c2e7b..d39e605623e 100644
--- a/src/vs/workbench/electron-sandbox/desktop.contribution.ts
+++ b/src/vs/workbench/electron-sandbox/desktop.contribution.ts
@@ -169,6 +169,7 @@ import product from 'vs/platform/product/common/product';
 			'window.zoomLevel': {
 				'type': 'number',
 				'default': 0,
+				'minimum': -5,
 				'description': localize('zoomLevel', "Adjust the zoom level of the window. The original size is 0 and each increment above (e.g. 1) or below (e.g. -1) represents zooming 20% larger or smaller. You can also enter decimals to adjust the zoom level with a finer granularity."),
 				ignoreSync: true,
 				tags: ['accessibility']