diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 26c8c56..2fe4917 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn
@@ -678,6 +678,7 @@
     "trees/layer_tree_host_unittest_context.cc",
     "trees/layer_tree_host_unittest_copyrequest.cc",
     "trees/layer_tree_host_unittest_damage.cc",
+    "trees/layer_tree_host_unittest_masks.cc",
     "trees/layer_tree_host_unittest_occlusion.cc",
     "trees/layer_tree_host_unittest_picture.cc",
     "trees/layer_tree_host_unittest_proxy.cc",