diff --git a/dwds/debug_extension_mv3/build.yaml b/dwds/debug_extension_mv3/build.yaml
index a1cdac35e..3785809c2 100644
--- a/dwds/debug_extension_mv3/build.yaml
+++ b/dwds/debug_extension_mv3/build.yaml
@@ -13,6 +13,7 @@ targets:
       
 builders:
   client_js_copy_builder:
+    required_inputs: [".js", ".png", ".html", ".css", ".json"]
     import: "tool/copy_builder.dart"
     builder_factories:
         - copyBuilder