diff --git a/app/.eslintrc b/app/.eslintrc
index bc2c1ce8..92153f57 100644
--- a/app/.eslintrc
+++ b/app/.eslintrc
@@ -29,7 +29,8 @@
     "comma-spacing": ["warn"],
     "camelcase": ["warn", {"ignoreDestructuring": true ,"properties": "never"}],
     "eol-last": ["warn", "always"],
-    "no-multiple-empty-lines": ["warn", {"max": 1}]
+    "no-multiple-empty-lines": ["warn", {"max": 1}],
+    "prefer-const": "warn"
   },
   "plugins": [
     "jest",
diff --git a/app/src/frontend/building-edit.js b/app/src/frontend/building-edit.js
index 79ff02c1..61b29efb 100644
--- a/app/src/frontend/building-edit.js
+++ b/app/src/frontend/building-edit.js
@@ -52,7 +52,7 @@ class EditForm extends Component {
     constructor(props) {
         super(props);
         this.state = {}
-        for (let field of props.fields) {
+        for (const field of props.fields) {
             this.state[field.slug] = props[field.slug]
         }
         this.state.error = this.props.error || undefined;
diff --git a/app/src/frontend/overview.js b/app/src/frontend/overview.js
index 52c2230b..095974d8 100644
--- a/app/src/frontend/overview.js
+++ b/app/src/frontend/overview.js
@@ -16,8 +16,8 @@ const Overview = (props) => {
         return <Redirect to="/sign-up.html" />
     }
 
-    let title = (props.mode === 'view')? 'View maps' : 'Add or edit data';
-    let back = (props.mode === 'edit')? `/view/${dataLayer}.html` : undefined;
+    const title = (props.mode === 'view')? 'View maps' : 'Add or edit data';
+    const back = (props.mode === 'edit')? `/view/${dataLayer}.html` : undefined;
 
     return (
         <Sidebar title={title} back={back}>