diff --git a/docs/webpack.md b/docs/webpack.md
index 9d4a812c2..dc59e4de6 100644
--- a/docs/webpack.md
+++ b/docs/webpack.md
@@ -1,6 +1,6 @@
-# Webpack 2
+# Webpack 2/3/4
 
-`modular-css/webpack/plugin` provides a webpack 2 plugin you can use to transform imported `.css` files into lookup objects while outputting CSS to disk.
+`modular-css/webpack/plugin` provides a webpack 2/3/4 plugin you can use to transform imported `.css` files into lookup objects while outputting CSS to disk.
 
 `modular-css/webpack/loader` provides the file loader that does the actual transformation on files.
 
@@ -66,4 +66,4 @@ All other options are passed to the underlying `Processor` instance, see [Option
 
 ### `namedExports`
 
-Set to `false` to disable named exports, instead only the default export wll be used. This is useful to avoid warnings when your classes aren't valid JS identifiers.
+Set to `false` to disable named exports, instead only the default export will be used. This is useful to avoid warnings when your classes aren't valid JS identifiers.
diff --git a/packages/webpack/loader.js b/packages/webpack/loader.js
index ff94a35e3..870120012 100644
--- a/packages/webpack/loader.js
+++ b/packages/webpack/loader.js
@@ -8,7 +8,9 @@ var utils   = require("loader-utils"),
 module.exports = function(source) {
     var options   = utils.getOptions(this) || false,
         done      = this.async(),
-        processor = this.options.processor;
+        processor = this.options
+            ? this.options.processor // Webpack 2 & 3
+            : this._compiler.options.processor; // Webpack 4
 
     if(options.cjs) {
         this.emitWarning(
diff --git a/packages/webpack/package.json b/packages/webpack/package.json
index 538fc16ad..361483aa0 100644
--- a/packages/webpack/package.json
+++ b/packages/webpack/package.json
@@ -20,7 +20,7 @@
   ],
   "devDependencies": {
     "test-utils": "^8.0.0",
-    "webpack": "^3.5.6"
+    "webpack": "^4.1.0"
   },
   "dependencies": {
     "esutils": "^2.0.2",
diff --git a/packages/webpack/test/__snapshots__/simple.json b/packages/webpack/test/__snapshots__/simple.json
index 704b00a65..3e1f83563 100644
--- a/packages/webpack/test/__snapshots__/simple.json
+++ b/packages/webpack/test/__snapshots__/simple.json
@@ -3,7 +3,8 @@
     "byIdentifier": {
       "packages/webpack/test/specimens/simple.js": 0,
       "packages/webpack/loader.js!packages/webpack/test/specimens/simple.css": 1,
-      "packages/webpack/loader.js??ref--0!packages/webpack/test/specimens/simple.css": 2
+      "packages/webpack/loader.js??ref--0!packages/webpack/test/specimens/simple.css": 2,
+      "packages/webpack/loader.js??ref--4!packages/webpack/test/specimens/simple.css": 1
     },
     "usedIds": {
       "0": 0,
@@ -16,8 +17,9 @@
       "main": 0
     },
     "byBlocks": {},
-    "usedIds": {
-      "0": 0
-    }
+    "usedIds": [
+      0
+    ],
+    "bySource": {}
   }
 }
\ No newline at end of file