diff --git a/.travis.yml b/.travis.yml
index 7d69d74..e0cc348 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,4 +2,3 @@ language: node_js
 node_js:
   - '8'
   - '6'
-  - '4'
diff --git a/index.js b/index.js
index ce98441..e4444e0 100644
--- a/index.js
+++ b/index.js
@@ -1,2 +1,2 @@
 'use strict';
-module.exports = () => (/\bv?(?:0|[1-9]\d*)\.(?:0|[1-9]\d*)\.(?:0|[1-9]\d*)(?:-[\da-z-]+(?:\.[\da-z-]+)*)?(?:\+[\da-z-]+(?:\.[\da-z-]+)*)?\b/ig);
+module.exports = () => /\bv?(?:0|[1-9]\d*)\.(?:0|[1-9]\d*)\.(?:0|[1-9]\d*)(?:-[\da-z-]+(?:\.[\da-z-]+)*)?(?:\+[\da-z-]+(?:\.[\da-z-]+)*)?\b/ig;
diff --git a/package.json b/package.json
index c7907af..fcb4070 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,7 @@
 		"url": "sindresorhus.com"
 	},
 	"engines": {
-		"node": ">=4"
+		"node": ">=6"
 	},
 	"scripts": {
 		"test": "xo && ava"
diff --git a/test.js b/test.js
index 829ca09..738e820 100644
--- a/test.js
+++ b/test.js
@@ -31,7 +31,7 @@ test('returns semver on match', t => {
 	t.deepEqual('foo 0.0.0 bar 0.1.1'.match(m()), ['0.0.0', '0.1.1']);
 });
 
-// See: https://github.com/sindresorhus/semver-regex/issues/7
-test.failing('doesn not return tag prefix', t => {
+// See #7
+test.failing('does not return tag prefix', t => {
 	t.deepEqual('v0.0.0'.match(m()), ['0.0.0']);
 });