diff --git a/gr-checks/BUILD b/gr-checks/BUILD
index eaab31d..3889aae 100644
--- a/gr-checks/BUILD
+++ b/gr-checks/BUILD
@@ -21,6 +21,7 @@
     entry_point = "gr-checks.js",
     rollup_bin = "//tools/node_tools:rollup-bin",
     sourcemap = "hidden",
+    format = 'iife',
     deps = [
         "@tools_npm//rollup-plugin-node-resolve",
     ],