diff --git a/src/components/IndexTreeBlock.tsx b/src/components/IndexTreeBlock.tsx
index 149b9b0..62e4115 100644
--- a/src/components/IndexTreeBlock.tsx
+++ b/src/components/IndexTreeBlock.tsx
@@ -9,10 +9,10 @@ import treeJson from '../assets/tree.json';
 interface IProps extends RouteComponentProps<{}, StaticContext, any> { }
 
 interface IState {
-    expandableKeys?: string[];
-    treeElement?: JSX.Element[];
-    expandedKeys?: string[];
-    selectedKeys?: string[];
+    expandableKeys: string[];
+    treeElement: JSX.Element[];
+    expandedKeys: string[];
+    selectedKeys: string[];
 }
 
 interface ITreeJson {
@@ -81,10 +81,12 @@ class IndexTreeBlock extends Component<IProps, IState> {
             });
         };
         const data: ITreeJson[] = treeJson;
-        const treeData: JSX.Element[] = loop(data);
-        this.setState({ treeElement: treeData });
-        this.setState({ expandedKeys: expandedKeys });
-        this.setState({ expandableKeys: expandedKeys });
+        const treeElement: JSX.Element[] = loop(data);
+        this.setState({
+            treeElement,
+            expandedKeys,
+            expandableKeys: expandedKeys
+        });
     }
 
     render() {