diff --git a/changelog.md b/changelog.md
index 0ced316..953f9ba 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 2026-04-30 - 2.10.1 - fix(mod_custom)
+make base64ts bundle output deterministic and clean up generated temp sourcemaps
+
+- Use a stable temporary bundle filename instead of a timestamp-based name so repeated base64ts builds produce identical output.
+- Delete the generated temporary sourcemap alongside the temp bundle to avoid leftover build artifacts.
+- Add a test covering deterministic base64ts output generation.
+- Update package scripts to use pnpm for tests and remove the allowimplicitany build flag.
+
 ## 2026-03-24 - 2.10.0 - feat(config)
 migrate project configuration to smartconfig.json and update bundler dependencies
 
diff --git a/package.json b/package.json
index 9c803f3..f3262e6 100644
--- a/package.json
+++ b/package.json
@@ -9,8 +9,8 @@
   "author": "Lossless GmbH",
   "license": "MIT",
   "scripts": {
-    "test": "npm run build && (tstest test/ --verbose)",
-    "build": "(tsbuild --web --allowimplicitany)",
+    "test": "pnpm run build && (tstest test/ --verbose)",
+    "build": "(tsbuild --web)",
     "buildDocs": "tsdoc"
   },
   "bin": {
diff --git a/test/test.ts b/test/test.ts
index cff5d37..07c545b 100644
--- a/test/test.ts
+++ b/test/test.ts
@@ -1,5 +1,6 @@
 import { expect, tap } from '@git.zone/tstest/tapbundle';
 import * as tsbundle from '../dist_ts/index.js';
+import { CustomBundleHandler } from '../dist_ts/mod_custom/index.js';
 import * as path from 'path';
 import * as fs from 'fs';
 
@@ -61,6 +62,30 @@ tap.test('should bundle with rspack in production mode', async () => {
   await testBundler('rspack', 'production');
 });
 
+tap.test('should generate deterministic base64ts output', async () => {
+  const testDir = path.join(process.cwd(), 'test');
+  const outputPath = path.join(testDir, 'dist_manual/base64-output.ts');
+  const bundleConfig = {
+    from: './ts_web/index.ts',
+    to: './dist_manual/base64-output.ts',
+    outputMode: 'base64ts' as const,
+    bundler: 'esbuild' as const,
+  };
+
+  const handler = new CustomBundleHandler(testDir);
+  if (fs.existsSync(outputPath)) {
+    fs.rmSync(outputPath, { force: true });
+  }
+
+  await handler.processSingleBundle(bundleConfig);
+  const firstOutput = fs.readFileSync(outputPath, 'utf8');
+
+  await handler.processSingleBundle(bundleConfig);
+  const secondOutput = fs.readFileSync(outputPath, 'utf8');
+
+  expect(secondOutput).toEqual(firstOutput);
+});
+
 // Test size comparison
 tap.test('should show bundle size comparison', async () => {
   const testDir = path.join(process.cwd(), 'test');
diff --git a/ts/00_commitinfo_data.ts b/ts/00_commitinfo_data.ts
index 91e36df..ea5e10c 100644
--- a/ts/00_commitinfo_data.ts
+++ b/ts/00_commitinfo_data.ts
@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@git.zone/tsbundle',
-  version: '2.10.0',
+  version: '2.10.1',
   description: 'a multi-bundler tool supporting esbuild, rolldown, and rspack for painless bundling of web projects'
 }
diff --git a/ts/mod_custom/index.ts b/ts/mod_custom/index.ts
index dfe005c..1d135ad 100644
--- a/ts/mod_custom/index.ts
+++ b/ts/mod_custom/index.ts
@@ -9,7 +9,7 @@ const TEMP_DIR = '.nogit/tsbundle-temp';
 
 export class CustomBundleHandler {
   private cwd: string;
-  private config: interfaces.ITsbundleConfig;
+  private config!: interfaces.ITsbundleConfig;
 
   constructor(cwd: string = paths.cwd) {
     this.cwd = cwd;
@@ -54,7 +54,7 @@ export class CustomBundleHandler {
 
     // Determine temp output path
     const tempDir = plugins.path.join(this.cwd, TEMP_DIR);
-    const tempBundlePath = plugins.path.join(tempDir, `bundle-${Date.now()}.js`);
+    const tempBundlePath = plugins.path.join(tempDir, 'bundle.js');
 
     // Ensure temp directory exists
     await plugins.fs.directory(tempDir).create();
@@ -88,6 +88,11 @@ export class CustomBundleHandler {
     if (tempFileExists) {
       await plugins.fs.file(tempBundlePath).delete();
     }
+    const tempSourceMapPath = `${tempBundlePath}.map`;
+    const tempSourceMapExists = await plugins.fs.file(tempSourceMapPath).exists();
+    if (tempSourceMapExists) {
+      await plugins.fs.file(tempSourceMapPath).delete();
+    }
   }
 
   /**