diff --git a/test/addons-napi/test_constructor/test.js b/test/addons-napi/test_constructor/test.js
index 92440bf49e74c1..26083db7a28a21 100644
--- a/test/addons-napi/test_constructor/test.js
+++ b/test/addons-napi/test_constructor/test.js
@@ -22,14 +22,14 @@ const propertyNames = [];
 for (const name in test_object) {
   propertyNames.push(name);
 }
-assert.ok(propertyNames.indexOf('echo') >= 0);
-assert.ok(propertyNames.indexOf('readwriteValue') >= 0);
-assert.ok(propertyNames.indexOf('readonlyValue') >= 0);
-assert.ok(propertyNames.indexOf('hiddenValue') < 0);
-assert.ok(propertyNames.indexOf('readwriteAccessor1') < 0);
-assert.ok(propertyNames.indexOf('readwriteAccessor2') < 0);
-assert.ok(propertyNames.indexOf('readonlyAccessor1') < 0);
-assert.ok(propertyNames.indexOf('readonlyAccessor2') < 0);
+assert.ok(propertyNames.includes('echo'));
+assert.ok(propertyNames.includes('readwriteValue'));
+assert.ok(propertyNames.includes('readonlyValue'));
+assert.ok(!propertyNames.includes('hiddenValue'));
+assert.ok(!propertyNames.includes('readwriteAccessor1'));
+assert.ok(!propertyNames.includes('readwriteAccessor2'));
+assert.ok(!propertyNames.includes('readonlyAccessor1'));
+assert.ok(!propertyNames.includes('readonlyAccessor2'));
 
 // The napi_writable attribute should be ignored for accessors.
 test_object.readwriteAccessor1 = 1;
diff --git a/test/addons-napi/test_properties/test.js b/test/addons-napi/test_properties/test.js
index 868c603879f1a2..a8127a27860eb3 100644
--- a/test/addons-napi/test_properties/test.js
+++ b/test/addons-napi/test_properties/test.js
@@ -21,14 +21,14 @@ const propertyNames = [];
 for (const name in test_object) {
   propertyNames.push(name);
 }
-assert.ok(propertyNames.indexOf('echo') >= 0);
-assert.ok(propertyNames.indexOf('readwriteValue') >= 0);
-assert.ok(propertyNames.indexOf('readonlyValue') >= 0);
-assert.ok(propertyNames.indexOf('hiddenValue') < 0);
-assert.ok(propertyNames.indexOf('readwriteAccessor1') < 0);
-assert.ok(propertyNames.indexOf('readwriteAccessor2') < 0);
-assert.ok(propertyNames.indexOf('readonlyAccessor1') < 0);
-assert.ok(propertyNames.indexOf('readonlyAccessor2') < 0);
+assert.ok(propertyNames.includes('echo'));
+assert.ok(propertyNames.includes('readwriteValue'));
+assert.ok(propertyNames.includes('readonlyValue'));
+assert.ok(!propertyNames.includes('hiddenValue'));
+assert.ok(!propertyNames.includes('readwriteAccessor1'));
+assert.ok(!propertyNames.includes('readwriteAccessor2'));
+assert.ok(!propertyNames.includes('readonlyAccessor1'));
+assert.ok(!propertyNames.includes('readonlyAccessor2'));
 
 // The napi_writable attribute should be ignored for accessors.
 test_object.readwriteAccessor1 = 1;