diff --git a/lib/binding_web/script/build.js b/lib/binding_web/script/build.js
index 6f2bedd6..737267a1 100644
--- a/lib/binding_web/script/build.js
+++ b/lib/binding_web/script/build.js
@@ -1,49 +1,37 @@
 import esbuild from 'esbuild';
 import fs from 'fs/promises';
-import path from 'path';
 
 const format = process.env.CJS ? 'cjs' : 'esm';
 const debug = process.argv.includes('--debug');
 const outfile = `${debug ? 'debug/' : ''}web-tree-sitter.${format === 'esm' ? 'js' : 'cjs'}`;
 
-// Copy source files to lib directory - we'll map the Wasm's sourcemap to these files.
-async function copySourceFiles() {
-  const sourceDir = '../src';
-  const files = await fs.readdir(sourceDir);
-
-  for (const file of files) {
-    if (file.endsWith('.c') || file.endsWith('.h')) {
-      await fs.copyFile(
-        path.join(sourceDir, file),
-        path.join('lib', file)
-      );
-    }
-  }
-}
-
 async function processWasmSourceMap(inputPath, outputPath) {
   const mapContent = await fs.readFile(inputPath, 'utf8');
   const sourceMap = JSON.parse(mapContent);
 
-  // Filter out emscripten files and normalize paths
-  sourceMap.sources = sourceMap.sources
-    .filter(source => {
-      // Keep only tree-sitter source files
-      return source.includes('../../src/') || source === 'tree-sitter.c';
-    })
-    .map(source => {
-      if (source.includes('../../src/')) {
-        return source.replace('../../src/', debug ? '../lib/' : 'lib/');
-      } else if (source === 'tree-sitter.c') {
-        return debug ? '../lib/tree-sitter.c' : 'lib/tree-sitter.c';
-      } else {
-        return source;
-      }
-    });
+  const isTreeSitterSource = (source) => 
+    source.includes('../../src/') || source === 'tree-sitter.c';
+
+  const normalizePath = (source) => {
+    if (source.includes('../../src/')) {
+      return source.replace('../../src/', debug ? '../lib/' : 'lib/');
+    } else if (source === 'tree-sitter.c') {
+      return debug ? '../lib/tree-sitter.c' : 'lib/tree-sitter.c';
+    }
+    return source;
+  };
+
+  const filtered = sourceMap.sources
+    .map((source, index) => ({ source, content: sourceMap.sourcesContent?.[index] }))
+    .filter(item => isTreeSitterSource(item.source))
+    .map(item => ({ source: normalizePath(item.source), content: item.content }));
+
+  sourceMap.sources = filtered.map(item => item.source);
+  sourceMap.sourcesContent = filtered.map(item => item.content);
+
   await fs.writeFile(outputPath, JSON.stringify(sourceMap, null, 2));
 }
 
-
 async function build() {
   await esbuild.build({
     entryPoints: ['src/index.ts'],
@@ -62,7 +50,6 @@ async function build() {
   const outputWasmName = `${debug ? 'debug/' : ''}web-tree-sitter.wasm`;
   await fs.copyFile('lib/web-tree-sitter.wasm', outputWasmName);
 
-  await copySourceFiles();
   await processWasmSourceMap('lib/web-tree-sitter.wasm.map', `${outputWasmName}.map`);
 }