diff --git a/.jshintrc b/.jshintrc
index 07d9631..eeccdcd 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -42,7 +42,7 @@
     "boss"          : false,     // true: Tolerate assignments where comparisons would be expected
     "debug"         : false,     // true: Allow debugger statements e.g. browser breakpoints.
     "eqnull"        : false,     // true: Tolerate use of `== null`
-    "esversion"     : 5,         // {int} Specify the ECMAScript version to which the code must adhere.
+    "esversion"     : 9,         // {int} Specify the ECMAScript version to which the code must adhere.
     "moz"           : false,     // true: Allow Mozilla specific syntax (extends and overrides esnext features)
                                  // (ex: `for each`, multiple try/catch, function expression…)
     "evil"          : false,     // true: Tolerate use of `eval` and `new Function()`
diff --git a/test/integration/proxyReqPathResolver.js b/test/integration/proxyReqPathResolver.js
index a2b9c16..12eb100 100644
--- a/test/integration/proxyReqPathResolver.js
+++ b/test/integration/proxyReqPathResolver.js
@@ -35,10 +35,10 @@ describe('resolveProxyReqPath', function() {
 
     agent(app.callback())
       .get('/working')
-      .end(() => {
+      .end(function() {
         assert.deepStrictEqual(opts.headers, {});
         done();
-      })
+      });
   });
 
   describe('when author uses option proxyReqPathResolver', function() {