diff --git a/.travis.yml b/.travis.yml
index 7d69d74..2ae9d62 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,5 @@
 language: node_js
 node_js:
+  - '10'
   - '8'
   - '6'
-  - '4'
diff --git a/appveyor.yml b/appveyor.yml
index 61c903a..49d58b5 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,8 +1,8 @@
 environment:
   matrix:
+    - nodejs_version: '10'
     - nodejs_version: '8'
     - nodejs_version: '6'
-    - nodejs_version: '4'
 install:
   - ps: Install-Product node $env:nodejs_version
   - set CI=true
diff --git a/index.js b/index.js
index de6662d..293b1b7 100644
--- a/index.js
+++ b/index.js
@@ -77,8 +77,8 @@ module.exports = opts => buf => {
 		input: buf,
 		bin: cwebp,
 		args
-	}).catch(err => {
-		err.message = err.stderr || err.message;
-		throw err;
+	}).catch(error => {
+		error.message = error.stderr || error.message;
+		throw error;
 	});
 };
diff --git a/package.json b/package.json
index 305c7e8..8383fbc 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,7 @@
     }
   ],
   "engines": {
-    "node": ">=4"
+    "node": ">=6"
   },
   "scripts": {
     "test": "xo && ava"
@@ -43,14 +43,14 @@
     "webp"
   ],
   "dependencies": {
-    "cwebp-bin": "^4.0.0",
+    "cwebp-bin": "^5.0.0",
     "exec-buffer": "^3.0.0",
     "is-cwebp-readable": "^2.0.1"
   },
   "devDependencies": {
-    "ava": "*",
+    "ava": "^0.25.0",
     "is-webp": "^1.0.0",
-    "pify": "^3.0.0",
-    "xo": "*"
+    "pify": "^4.0.0",
+    "xo": "^0.23.0"
   }
 }