diff --git a/src/WorkerPool.js b/src/WorkerPool.js
index 86d091c..ba4bd72 100644
--- a/src/WorkerPool.js
+++ b/src/WorkerPool.js
@@ -7,6 +7,7 @@ import asyncMapSeries from 'neo-async/mapSeries';
 
 import readBuffer from './readBuffer';
 import WorkerError from './WorkerError';
+import { replacer, reviver } from './serializer';
 
 const workerPath = require.resolve('./worker');
 
@@ -107,7 +108,7 @@ class PoolWorker {
 
   writeJson(data) {
     const lengthBuffer = Buffer.alloc(4);
-    const messageBuffer = Buffer.from(JSON.stringify(data), 'utf-8');
+    const messageBuffer = Buffer.from(JSON.stringify(data, replacer), 'utf-8');
     lengthBuffer.writeInt32BE(messageBuffer.length, 0);
     this.writePipe.write(lengthBuffer);
     this.writePipe.write(messageBuffer);
@@ -141,7 +142,7 @@ class PoolWorker {
         }
         this.state = 'message read';
         const messageString = messageBuffer.toString('utf-8');
-        const message = JSON.parse(messageString);
+        const message = JSON.parse(messageString, reviver);
         this.state = 'process message';
         this.onWorkerMessage(message, (err) => {
           if (err) {
diff --git a/src/serializer.js b/src/serializer.js
new file mode 100644
index 0000000..a27098a
--- /dev/null
+++ b/src/serializer.js
@@ -0,0 +1,21 @@
+export function replacer(_key, value) {
+  if (value instanceof RegExp) {
+    return {
+      __serialized_type: 'RegExp',
+      source: value.source,
+      flags: value.flags,
+    };
+  }
+  return value;
+}
+
+export function reviver(_key, value) {
+  if (typeof value === 'object' && value !== null) {
+    // eslint-disable-next-line no-underscore-dangle
+    if (value.__serialized_type === 'RegExp') {
+      return new RegExp(value.source, value.flags);
+    }
+  }
+
+  return value;
+}
diff --git a/src/worker.js b/src/worker.js
index 2a02910..e6e8724 100644
--- a/src/worker.js
+++ b/src/worker.js
@@ -6,6 +6,7 @@ import loaderRunner from 'loader-runner';
 import asyncQueue from 'neo-async/queue';
 
 import readBuffer from './readBuffer';
+import { replacer, reviver } from './serializer';
 
 const writePipe = fs.createWriteStream(null, { fd: 3 });
 const readPipe = fs.createReadStream(null, { fd: 4 });
@@ -93,7 +94,7 @@ function writeJson(data) {
   });
 
   const lengthBuffer = Buffer.alloc(4);
-  const messageBuffer = Buffer.from(JSON.stringify(data), 'utf-8');
+  const messageBuffer = Buffer.from(JSON.stringify(data, replacer), 'utf-8');
   lengthBuffer.writeInt32BE(messageBuffer.length, 0);
 
   writePipeWrite(lengthBuffer);
@@ -319,7 +320,7 @@ function readNextMessage() {
         return;
       }
       const messageString = messageBuffer.toString('utf-8');
-      const message = JSON.parse(messageString);
+      const message = JSON.parse(messageString, reviver);
 
       onMessage(message);
       setImmediate(() => readNextMessage());
diff --git a/test/sass-loader-example/assets/color_palette.scss b/test/sass-loader-example/assets/color_palette.scss
new file mode 100644
index 0000000..f84acf0
--- /dev/null
+++ b/test/sass-loader-example/assets/color_palette.scss
@@ -0,0 +1 @@
+$white: #FFFFFF;
diff --git a/test/sass-loader-example/style.scss b/test/sass-loader-example/style.scss
index f4daeb7..ba183c6 100644
--- a/test/sass-loader-example/style.scss
+++ b/test/sass-loader-example/style.scss
@@ -1,4 +1,5 @@
 @import '_shared';
+@import 'color_palette';
 
 body {
   background: red;
diff --git a/test/sass-loader-example/webpack.config.js b/test/sass-loader-example/webpack.config.js
index b0a3918..5624ddb 100644
--- a/test/sass-loader-example/webpack.config.js
+++ b/test/sass-loader-example/webpack.config.js
@@ -16,6 +16,9 @@ module.exports = (env) => {
   };
   const sassLoaderOptions = {
     sourceMap: true,
+    sassOptions: {
+      includePaths: [path.resolve(__dirname, 'assets')],
+    },
   };
   if (+env.threads > 0) {
     threadLoader.warmup(workerPool, ['babel-loader', 'babel-preset-env']);
diff --git a/test/serializer.test.js b/test/serializer.test.js
new file mode 100644
index 0000000..a39e444
--- /dev/null
+++ b/test/serializer.test.js
@@ -0,0 +1,31 @@
+const { replacer, reviver } = require('../src/serializer');
+
+test('round-trips plain objects', () => {
+  const json = JSON.stringify(
+    {
+      a: 1,
+      b: 'foo',
+      c: [null, false],
+    },
+    replacer
+  );
+  expect(JSON.parse(json, reviver)).toEqual({
+    a: 1,
+    b: 'foo',
+    c: [null, false],
+  });
+});
+
+test('round-trips regular expressions', () => {
+  const json = JSON.stringify(
+    {
+      r: /hoge/g,
+      s: /^(\w\s)+$/m,
+    },
+    replacer
+  );
+  expect(JSON.parse(json, reviver)).toEqual({
+    r: /hoge/g,
+    s: /^(\w\s)+$/m,
+  });
+});