upgrade to postcss version 4

index.js

@@ -31,7 +31,7 @@ module.exports = function (options) {
                 value = value.replace(pxRegex, pxReplace);
 
                 // if rem unit already exists, do not add or replace
-                if (remExists(rule.decls, decl.prop, value)) return;
+                if (remExists(rule, decl.prop, value)) return;
 
                 if (replace) {
                     decl.value = value;
@@ -64,4 +64,4 @@ function remExists(decls, prop, value) {
     return decls.some(function (decl) {
         return (decl.prop === prop && decl.value === value);
     });
-}
+}

package.json

@@ -1,26 +1,26 @@
 {
-    "name": "pxtorem",
-    "description": "A CSS post-processor that converts px to rem.",
-    "version": "1.0.1",
-    "author": "cuth",
-    "license": "MIT",
-    "repository": {
-        "type": "git",
-        "url": "git://github.com/cuth/pxtorem"
-    },
-    "bugs": "https://github.com/cuth/pxtorem/issues",
-    "main": "index.js",
-    "scripts": {
-        "test": "jasmine-node spec"
-    },
-    "devDependencies": {
-        "postcss": "^2.1.0",
-        "jasmine-node": "~1.11.0"
-    },
-    "keywords": [
-        "css",
-        "rem",
-        "postcss",
-        "postcss-plugin"
-    ]
+  "name": "pxtorem",
+  "description": "A CSS post-processor that converts px to rem.",
+  "version": "1.0.1",
+  "author": "cuth",
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/cuth/pxtorem"
+  },
+  "bugs": "https://github.com/cuth/pxtorem/issues",
+  "main": "index.js",
+  "scripts": {
+    "test": "jasmine-node spec"
+  },
+  "devDependencies": {
+    "jasmine-node": "~1.11.0",
+    "postcss": "^4.0.3"
+  },
+  "keywords": [
+    "css",
+    "rem",
+    "postcss",
+    "postcss-plugin"
+  ]
 }