diff --git a/index-wasm-esm.js b/index-wasm-esm.mjs
similarity index 100%
rename from index-wasm-esm.js
rename to index-wasm-esm.mjs
diff --git a/index.js b/index.mjs
similarity index 100%
rename from index.js
rename to index.mjs
diff --git a/node.js b/node.mjs
similarity index 100%
rename from node.js
rename to node.mjs
diff --git a/package.json b/package.json
index 9e0a8368d..d89d931b0 100644
--- a/package.json
+++ b/package.json
@@ -38,11 +38,11 @@
         }
     },
     "files": [
-        "index.js",
+        "index.mjs",
         "index.cjs",
-        "index-wasm-esm.js",
+        "index-wasm-esm.mjs",
         "index.d.ts",
-        "node.js",
+        "node.mjs",
         "node.cjs",
         "pkg/matrix_sdk_crypto_wasm.d.ts",
         "pkg/matrix_sdk_crypto_wasm_bg.js",