diff --git a/.gitignore b/.gitignore
index 8bfec3e..93f1361 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,2 @@
 node_modules
 npm-debug.log
-index.js
diff --git a/contributing.md b/contributing.md
index d398520..125417e 100644
--- a/contributing.md
+++ b/contributing.md
@@ -2,6 +2,12 @@
 
 We welcome contributions. Please provide pull requests and notify @springmeyer for review.
 
+### Changing index.js
+
+Do not change index.js directly as it is generated. Modify index._ instead and run
+`node generate.js` instead. If the node binary is differently named on your operating
+system (e.g. nodejs) use that instead.
+
 ### Releasing
 
 1) Create a milestone for the upcoming release
@@ -50,4 +56,3 @@ NOTE: make sure your git checkout is clean first: `git status` should show no ch
 ```bash
 npm publish
 ```
-
diff --git a/index._ b/index._
index c3d6824..35eb297 100644
--- a/index._
+++ b/index._
@@ -1,3 +1,8 @@
+/*
+THIS FILE IS GENERATED PROGAMMATICALLY. DO NOT MODIFIY DIRECTLY.
+Modify index._ instead and run node generate.js
+*/
+
 var path = require('path');
 var semver = require('semver');
 
diff --git a/index.js b/index.js
new file mode 100644
index 0000000..158da93
--- /dev/null
+++ b/index.js
@@ -0,0 +1,124 @@
+/*
+THIS FILE IS GENERATED PROGAMMATICALLY. DO NOT MODIFIY DIRECTLY.
+Modify index._ instead and run node generate.js
+*/
+
+var path = require('path');
+var semver = require('semver');
+
+
+var versions = [
+    '2.0.0',
+    '2.0.1',
+    '2.0.2',
+    '2.1.0',
+    '2.1.1',
+    '2.2.0',
+    '2.3.0',
+    '3.0.0',
+    '3.0.3',
+    '3.0.6'
+];
+
+// These older versions don't have the datasource info
+var no_datasources = [
+    '2.0.0',
+    '2.0.1',
+    '2.0.2',
+    '2.1.0',
+    '2.1.1',
+    '2.2.0'
+];
+module.exports.versions = versions;
+module.exports.latest = versions[versions.length - 1];
+
+var getSatisfyingVersion = function (wanted) {
+    var version = semver.maxSatisfying(versions, wanted), parsed;
+    if (!version) {
+        try {
+            parsed = semver(wanted);
+            parsed.patch = 'x';
+            version = semver.maxSatisfying(versions, parsed.format());
+        } catch (err) {
+            version = null;
+        }
+    }
+    return version;
+};
+
+var loadBrowser = function (version) {
+    var versionRefs = {
+       '2.0.0': {
+            'ref': require('./2.0.0/reference.json'),
+            'datasources': null
+        },
+       '2.0.1': {
+            'ref': require('./2.0.1/reference.json'),
+            'datasources': null
+        },
+       '2.0.2': {
+            'ref': require('./2.0.2/reference.json'),
+            'datasources': null
+        },
+       '2.1.0': {
+            'ref': require('./2.1.0/reference.json'),
+            'datasources': null
+        },
+       '2.1.1': {
+            'ref': require('./2.1.1/reference.json'),
+            'datasources': null
+        },
+       '2.2.0': {
+            'ref': require('./2.2.0/reference.json'),
+            'datasources': null
+        },
+       '2.3.0': {
+            'ref': require('./2.3.0/reference.json'),
+            'datasources': require('./2.3.0/datasources.json').datasources
+        },
+       '3.0.0': {
+            'ref': require('./3.0.0/reference.json'),
+            'datasources': require('./3.0.0/datasources.json').datasources
+        },
+       '3.0.3': {
+            'ref': require('./3.0.3/reference.json'),
+            'datasources': require('./3.0.3/datasources.json').datasources
+        },
+       '3.0.6': {
+            'ref': require('./3.0.6/reference.json'),
+            'datasources': require('./3.0.6/datasources.json').datasources
+        }
+    };
+
+    var ref = versionRefs[version].ref;
+    if (no_datasources.indexOf(version) <= -1) {
+        ref.datasources = versionRefs[version].datasources;
+    }
+
+    return ref;
+};
+
+var load = function (version) {
+    var ref = require(path.join(__dirname, version, 'reference.json'));
+    if (no_datasources.indexOf(version) <= -1) {
+        ref.datasources = require(path.join(__dirname, version, 'datasources.json')).datasources;
+    }
+
+    return ref;
+};
+
+module.exports.load = function(wanted) {
+    var version = getSatisfyingVersion(wanted),
+        ref;
+    if (!version) {
+        throw new Error("Unknown mapnik-reference version: '" + wanted + "'");
+    }
+    if (process.browser) {
+        ref = loadBrowser(version);
+    }
+    else {
+        ref = load(version);
+    }
+
+    return ref;
+}
diff --git a/package.json b/package.json
index b3f8b5c..0305c37 100644
--- a/package.json
+++ b/package.json
@@ -8,9 +8,7 @@
     "url": "git://github.com/mapnik/mapnik-reference.git"
   },
   "scripts": {
-    "test": "mocha -R spec --timeout 50000",
-    "prepublish": "node generate.js",
-    "postinstall": "node generate.js"
+    "test": "mocha -R spec --timeout 50000"
   },
   "devDependencies": {
     "glob": "4.x",