diff --git a/etc/package.json b/etc/package.json
new file mode 100644
index 0000000..6990891
--- /dev/null
+++ b/etc/package.json
@@ -0,0 +1 @@
+{"type": "module"}
diff --git a/package.json5 b/package.json5
index ebb3ed2..afa5263 100644
--- a/package.json5
+++ b/package.json5
@@ -3,7 +3,7 @@
    version: '0.0.1',
    description: 'Another prototype for a math core',
    scripts: {
-      build: 'tsc && echo {"type": "module"} > build/package.json',
+      build: 'tsc && cp etc/package.json build/',
       go: 'pnpm build && pnpm start',
       prepare: 'ts-patch install -s',
       start: 'node --experimental-loader tsc-module-loader build',