diff --git a/dom/base/Navigator.cpp b/dom/base/Navigator.cpp
index 2274826a2a23..12a41da241da 100644
--- a/dom/base/Navigator.cpp
+++ b/dom/base/Navigator.cpp
@@ -1607,9 +1607,10 @@ Navigator::HasFeature(const nsAString& aName, ErrorResult& aRv)
     return nullptr;
   }
 
-  // Hardcoded web-extensions feature which is b2g specific.
+  // Hardcoded extensions features which are b2g specific.
 #ifdef MOZ_B2G
-  if (aName.EqualsLiteral("web-extensions")) {
+  if (aName.EqualsLiteral("web-extensions") ||
+      aName.EqualsLiteral("late-customization")) {
     p->MaybeResolve(true);
     return p.forget();
   }
diff --git a/dom/base/test/test_hasFeature.html b/dom/base/test/test_hasFeature.html
index 7be3eb604937..fcc6ca809b6a 100644
--- a/dom/base/test/test_hasFeature.html
+++ b/dom/base/test/test_hasFeature.html
@@ -65,11 +65,19 @@ function testExtensions() {
     return Promise.resolve();
   }
 
-  return navigator.hasFeature("web-extensions").then(function(value) {
-    is(value, true, "Resolve the Promise with " + value + " for web-extensions");
-  }, function() {
-    ok(false, "The Promise should not be rejected");
+  var builtInFeatures = [
+    {feature: "web-extensions", value: true},
+    {feature: "late-customization", value: true}
+  ];
+
+  builtInFeatures.forEach(function(x) {
+    navigator.hasFeature(x.feature).then(function(value) {
+      is(value, x.value, "Resolve the Promise with " + value + " for feature: " + x.feature);
+    }).catch(function(ex) {
+      ok(false, "The Promise should not be rejected");
+    });
   });
+  return Promise.resolve();
 }
 
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