diff --git a/packages/wasm/src/index.ts b/packages/wasm/src/index.ts
index fcbca22d..9949785b 100644
--- a/packages/wasm/src/index.ts
+++ b/packages/wasm/src/index.ts
@@ -8,7 +8,10 @@ export function getWasmUrl(): URL {
     // making it not work. probably related to https://github.com/vitejs/vite/issues/8427,
     // but asking the user to deoptimize the entire @mtcute/web is definitely not a good idea
     // so we'll just use this hack for now
+    // @only-if-esm
     return new URL('../mtcute.wasm', import.meta.url)
+    // @/only-if-esm
+    throw new Error('ESM-only')
 }
 
 let wasm!: MtcuteWasmModule