diff --git a/package.json b/package.json
index 2dd2acf7..91a40934 100644
--- a/package.json
+++ b/package.json
@@ -43,9 +43,9 @@
     "!cosmos-sdk-*/**/*.md"
   ],
   "scripts": {
-    "format": "prettier --write --log-level warn \"./src/**/*.ts\" \"./scripts/**/*.js\"",
+    "format": "prettier --write --log-level warn \"./src/**/*.ts\" \"./scripts/**/*.cjs\"",
     "precodegen": "./scripts/exports_protos.sh",
-    "codegen": "rm -rf ./src && ./scripts/codegen.js && npm run format",
+    "codegen": "rm -rf ./src && ./scripts/codegen.cjs && npm run format",
     "prepare-publishing": "./scripts/prepare-publishing.sh",
     "build": "rm -rf ./build && tsc && npm run prepare-publishing"
   },
diff --git a/scripts/codegen.js b/scripts/codegen.cjs
similarity index 97%
rename from scripts/codegen.js
rename to scripts/codegen.cjs
index 4caa455e..d1535ca9 100755
--- a/scripts/codegen.js
+++ b/scripts/codegen.cjs
@@ -10,6 +10,7 @@ telescope({
   protoDirs: ["protos/cosmos-sdk", "protos/wasmd", "protos/ibc-go"],
   outPath: outPath,
   options: {
+    restoreImportExtension: ".ts",
     logLevel: 0,
     useSDKTypes: false,
     tsDisable: {
@@ -102,7 +103,7 @@ telescope({
 
     // Exports we want to provide at the root of the "cosmjs-types" package
 
-    export type { DeepPartial, Exact } from "./helpers";
+    export type { DeepPartial, Exact } from "./helpers.ts";
     `;
     writeFileSync(`${outPath}/index.ts`, index_ts);
 
diff --git a/src/index.ts b/src/index.ts
index bfe8ca12..65252145 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -2,4 +2,4 @@
 
 // Exports we want to provide at the root of the "cosmjs-types" package
 
-export type { DeepPartial, Exact } from "./helpers";
+export type { DeepPartial, Exact } from "./helpers.ts";
diff --git a/tsconfig.json b/tsconfig.json
index e7fa85e9..02a2eb15 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -21,6 +21,7 @@
     // So minifiers have to strip them off later on.
     "removeComments": false,
     "resolveJsonModule": true,
+    "rewriteRelativeImportExtensions": true,
     "rootDir": "src",
     "sourceMap": true,
     "strict": true