diff --git a/lib/webpack/createBaseConfig.js b/lib/webpack/createBaseConfig.js
index e56879f001..8ba10c249c 100644
--- a/lib/webpack/createBaseConfig.js
+++ b/lib/webpack/createBaseConfig.js
@@ -189,7 +189,7 @@ module.exports = function createBaseConfig ({
 
       rule.use('postcss-loader').loader('postcss-loader').options(Object.assign({
         plugins: [require('autoprefixer')],
-        sourceMap: !isProd
+        sourceMap: !isProd || debug
       }, siteConfig.postcss))
 
       if (loader) {