diff --git a/src/components/layers/MaxZoomBlock.jsx b/src/components/layers/MaxZoomBlock.jsx
index b2ba45d..1989de4 100644
--- a/src/components/layers/MaxZoomBlock.jsx
+++ b/src/components/layers/MaxZoomBlock.jsx
@@ -6,7 +6,7 @@ import NumberInput from '../inputs/NumberInput'
 
 class MaxZoomBlock extends React.Component {
   static propTypes = {
-    value: React.PropTypes.number.isRequired,
+    value: React.PropTypes.number,
     onChange: React.PropTypes.func.isRequired,
   }
 
diff --git a/src/components/layers/MinZoomBlock.jsx b/src/components/layers/MinZoomBlock.jsx
index c4a7f36..5483376 100644
--- a/src/components/layers/MinZoomBlock.jsx
+++ b/src/components/layers/MinZoomBlock.jsx
@@ -6,7 +6,7 @@ import NumberInput from '../inputs/NumberInput'
 
 class MinZoomBlock extends React.Component {
   static propTypes = {
-    value: React.PropTypes.number.isRequired,
+    value: React.PropTypes.number,
     onChange: React.PropTypes.func.isRequired,
   }