Match bazel's semantics for genrule cmd
diff --git a/demo/BUCK b/demo/BUCK
index 78e75e6..eebe5c2 100644
--- a/demo/BUCK
+++ b/demo/BUCK
@@ -1,3 +1,5 @@
+load("//tools/buck:genrule.bzl", "genrule")
+
 rust_binary(
     name = "demo",
     srcs = glob(["src/**/*.rs"]),