diff --git a/lib/index.ts b/lib/index.ts
index 6e744c4..0dc957f 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -182,8 +182,8 @@ export function bundle(options: Options): BundleResult {
             trace(generatedLine);
             mainFileContent += generatedLine + "\n";
         });
-        mainFile = path.resolve(baseDir, "dts-bundle.tmp." + exportName + ".d.ts");
-        fs.writeFileSync(mainFile, mainFileContent, 'utf8');
+        mainFile = path.resolve(baseDir, "dts-bundle.tmp." + exportName.replace(/[@\/]/g, '.') + ".d.ts");
+        fs.writeFileSync(mainFile, mainFileContent, { encoding: 'utf8' });
     }
 
     trace('\n### find typings ###');
@@ -424,7 +424,7 @@ export function bundle(options: Options): BundleResult {
             }
         }
 
-        fs.writeFileSync(outFile, content, 'utf8');
+        fs.writeFileSync(outFile, content, { encoding: 'utf8' });
         bundleResult.emitted = true;
     } else {
         warning(" XXX Not emit due to exist files not found.")
diff --git a/package.json b/package.json
index 548e1fe..5ce6a4d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "dts-bundle",
-  "version": "0.7.3",
+  "version": "0.7.4",
   "description": "Export TypeScript .d.ts files as an external module definition",
   "keywords": [
     "typescript",