diff --git a/packages/gatsby-plugin-postcss/package.json b/packages/gatsby-plugin-postcss/package.json
index 521a5a2b2ac01..82dc4e9ed8619 100644
--- a/packages/gatsby-plugin-postcss/package.json
+++ b/packages/gatsby-plugin-postcss/package.json
@@ -8,7 +8,7 @@
   },
   "dependencies": {
     "@babel/runtime": "^7.0.0",
-    "postcss-loader": "^3.0.0"
+    "postcss-loader": "^4.0.0"
   },
   "devDependencies": {
     "@babel/cli": "^7.0.0",