diff --git a/bin/carto b/bin/carto
index 1ef7cd8..91c672d 100755
--- a/bin/carto
+++ b/bin/carto
@@ -8,47 +8,33 @@ var path = require('path'),
 
 var existsSync = require('fs').existsSync || require('path').existsSync
 
-var args = process.argv.slice(1);
-var options = { nosymlink:false };
-
-args = args.filter(function (arg) {
-    var match;
-
-    if (match = arg.match(/^--?([a-z][0-9a-z-]*)$/i)) { arg = match[1] }
-    else { return arg }
-
-    switch (arg) {
-        case 'v':
-        case 'version':
-            console.log("carto " + carto.version.join('.') + " (Carto map stylesheet compiler)");
-            process.exit(0);
-            break;
-        case 'b':
-        case 'benchmark':
-            options.benchmark = true;
-            break;
-        case 'n':
-        case 'nosymlink':
-            options.nosymlink = true;
-            break;
-        default:
-            console.log("Usage: carto <source MML file>");
-            console.log("Options:");
-            console.log("  -v   --version      Parse JSON map manifest");
-            console.log("  -b   --benchmark    Outputs total compile time");
-            console.log("  -n   --nosymlink    Use absolute paths instead of symlinking files");
-            process.exit(0);
-            break;
-    }
-});
+var optimist = require('optimist')
+            .usage("Usage: $0 <source MML file>")
+            .options('h', {alias:'help', describe:'Display this help message'})
+            .options('v', {alias:'version', boolean:true, describe:'Display version information'})
+            .options('b', {alias:'benchmark', boolean:true, describe:'Outputs total compile time'})
+            .options('n', {alias:'nosymlink', boolean:true, describe:'Use absolute paths instead of symlinking files'})
+            .options('dpi', {describe:'Dpi used to convert m, mm, cm, pt, pc to pixels', default:90.714});
+
+var options = optimist.argv;
+
+if (options.help) {
+    optimist.showHelp();
+    process.exit(0);
+}
+
+if (options.version) {
+    console.log("carto " + carto.version.join('.') + " (Carto map stylesheet compiler)");
+    process.exit(0);
+}
 
-var input = args[1];
+var input = options._[0];
 if (input && input[0] != '/') {
     input = path.join(process.cwd(), input);
 }
 
 if (!input) {
-    console.log("carto: no input files");
+    console.log("carto: no input files ('carto --help' for help)");
     process.exit(1);
 }
 
@@ -76,7 +62,8 @@ function compileMML(err, data) {
     try {
         var renderer = new carto.Renderer({
             filename: input,
-            benchmark: options.benchmark
+            benchmark: options.benchmark,
+            dpi: options.dpi
         });
         renderer.render(data, function(err, output) {
             if (err) {
@@ -110,7 +97,8 @@ function compileMSS(err, data) {
     try {
         var renderer = new carto.Renderer({
             filename: path.basename(input),
-            benchmark: options.benchmark
+            benchmark: options.benchmark,
+            dpi:options.dpi
         });
         renderer.renderMSS(data, function(err, output) {
             if (err) {
diff --git a/package.json b/package.json
index b5fc3ff..5b63d71 100644
--- a/package.json
+++ b/package.json
@@ -4,8 +4,8 @@
   "description": "Mapnik Stylesheet Compiler",
   "url": "https://github.com/mapbox/carto",
   "repositories": [{
-    "type": "git",
-    "url": "http://github.com/mapbox/carto.git"
+      "type": "git",
+      "url": "http://github.com/mapbox/carto.git"
   }],
   "author": {
     "name": "MapBox",
@@ -37,7 +37,8 @@
   "dependencies": {
     "underscore": "~1.4.3",
     "mapnik-reference": "~5.0.3",
-    "xml2js": "~0.1.13"
+    "xml2js": "~0.1.13",
+    "optimist": "~0.3.5"
   },
   "devDependencies": {
     "mocha": "1.7.x",