diff --git a/packages/rspack/lib/config.js b/packages/rspack/lib/config.js
index 88c0e4cd9a..24fc73a6d9 100644
--- a/packages/rspack/lib/config.js
+++ b/packages/rspack/lib/config.js
@@ -20,6 +20,7 @@ const {
   isMeteorBlazeProject,
   isMeteorLessProject,
   isMeteorScssProject,
+  getMeteorEnvPackageDirs,
 } = require('meteor/tools-core/lib/meteor');
 
 import { getInitialEntrypoints } from './build-context';
@@ -107,11 +108,21 @@ export function configureMeteorForRspack() {
     dir => !includedDirs.includes(dir),
   );
 
+  const envPackageDirs = getMeteorEnvPackageDirs().map(
+    dir => path.normalize(dir)?.split(path.sep)?.filter(Boolean)?.[0],
+  );
   let extraFoldersToIgnore = [
     ...ignoredDirs
       .filter(
         dir =>
-          !['public', 'private', '.meteor', 'packages', RSPACK_BUILD_CONTEXT].includes(dir),
+          ![
+            'public',
+            'private',
+            '.meteor',
+            'packages',
+            ...envPackageDirs,
+            RSPACK_BUILD_CONTEXT,
+          ].includes(dir),
       )
       .map(dir => `${dir}/**`),
   ];
diff --git a/packages/tools-core/lib/meteor.js b/packages/tools-core/lib/meteor.js
index 47b2c8eae5..5dec528f61 100644
--- a/packages/tools-core/lib/meteor.js
+++ b/packages/tools-core/lib/meteor.js
@@ -411,3 +411,19 @@ export function isMeteorBundleVisualizerProject() {
 export function isMeteorPackagesTest() {
   return Package?.meteor?.global?.currentCommand?.name === 'test-packages';
 }
+
+/**
+ * Gets the package directories from the environment variables.
+ * @returns {string[]}
+ */
+export function getMeteorEnvPackageDirs() {
+  function packageDirsFromEnvVar(envVar, delimiter = path.delimiter) {
+    return process.env[envVar] && process.env[envVar].split(delimiter) || [];
+  }
+  return [
+    // METEOR_PACKAGE_DIRS should use the arch-specific delimiter
+    ...(packageDirsFromEnvVar('METEOR_PACKAGE_DIRS', path.delimiter || ':')),
+    // PACKAGE_DIRS (deprecated) always used ':' separator (yes, even Windows)
+    ...(packageDirsFromEnvVar('PACKAGE_DIRS', ':')),
+  ];
+}