diff --git a/svelte.config.js b/svelte.config.js
new file mode 100644
index 0000000..5f08be0
--- /dev/null
+++ b/svelte.config.js
@@ -0,0 +1,7 @@
+// Note: this file cannot be named .mjs because snowpack-plugin svelte looks for file with .js extension
+const preprocess = require('svelte-preprocess')
+
+module.exports = {
+  dev: process.env.NODE_ENV === 'development',
+  preprocess: preprocess({typescript: {compilerOptions: {target: 'esnext'}}})
+}
diff --git a/svelte.config.mjs b/svelte.config.mjs
deleted file mode 100644
index 5d8bdeb..0000000
--- a/svelte.config.mjs
+++ /dev/null
@@ -1,6 +0,0 @@
-import preprocess from 'svelte-preprocess'
-
-export default {
-  dev: process.env.NODE_ENV === 'development',
-  preprocess: preprocess({typescript: {compilerOptions: {target: 'esnext'}}})
-}