diff --git a/.changeset/neat-icons-fry.md b/.changeset/neat-icons-fry.md
new file mode 100644
index 0000000000..33c4a4512c
--- /dev/null
+++ b/.changeset/neat-icons-fry.md
@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Tweaked frontend bundling configuration to avoid leaking declarations into global scope.
diff --git a/packages/cli/src/lib/bundler/optimization.ts b/packages/cli/src/lib/bundler/optimization.ts
index a5cf38fc11..0a5ef178cb 100644
--- a/packages/cli/src/lib/bundler/optimization.ts
+++ b/packages/cli/src/lib/bundler/optimization.ts
@@ -29,6 +29,7 @@ export const optimization = (
     minimizer: [
       new ESBuildMinifyPlugin({
         target: 'es2019',
+        format: 'iife',
       }),
     ],
     runtimeChunk: 'single',