diff --git a/src/main/java/org/warcbase/data/UrlMappingBuilder.java b/src/main/java/org/warcbase/data/UrlMappingBuilder.java
index d0bb1ba..303b66b 100644
--- a/src/main/java/org/warcbase/data/UrlMappingBuilder.java
+++ b/src/main/java/org/warcbase/data/UrlMappingBuilder.java
@@ -1,90 +1,125 @@
 package org.warcbase.data;
 
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.CommandLineParser;
+import org.apache.commons.cli.GnuParser;
+import org.apache.commons.cli.HelpFormatter;
+import org.apache.commons.cli.OptionBuilder;
+import org.apache.commons.cli.Options;
+import org.apache.commons.cli.ParseException;
 import org.apache.commons.io.FileUtils;
+import org.apache.hadoop.util.ToolRunner;
 import org.apache.log4j.Logger;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.IntsRef;
 import org.apache.lucene.util.fst.Builder;
 import org.apache.lucene.util.fst.FST;
 import org.apache.lucene.util.fst.FST.INPUT_TYPE;
 import org.apache.lucene.util.fst.PositiveIntOutputs;
 import org.apache.lucene.util.fst.Util;
 
 public class UrlMappingBuilder {
   private static final Logger LOG = Logger.getLogger(UrlMappingBuilder.class);
 
   private static void readUrlFromFile(File f, List<String> urls) throws IOException {
     String contents = FileUtils.readFileToString(f);
     String[] lines = contents.split("\\n");
     for (String line : lines) {
       if (!line.equals("")) {
         String url = line.split("\\s+")[0];
         urls.add(url);
       }
     }
     LOG.info("Read " + f + ", " + urls.size() + " URLs");
   }
 
   private static List<String> readUrlFromFolder(String folderName) throws IOException {
     File folder = new File(folderName);
     List<String> urls = new ArrayList<String>();
     if (folder.isDirectory()) {
       for (File file : folder.listFiles()) {
         readUrlFromFile(file, urls);
       }
     } else {
       readUrlFromFile(folder, urls);
     }
 
     LOG.info("Sorting URLs...");
     Collections.sort(urls); // sort URLs alphabetically
     LOG.info("Done sorting!");
 
     return urls;
   }
 
+  public static final String INPUT_OPTION = "input";
+  public static final String OUTPUT_OPTION = "output";
+
+  @SuppressWarnings("static-access")
   public static void main(String[] args) throws IOException {
-    String inputFileName = new String();
-    String outputFileName = new String();
-    if (args.length > 0) { // read file name from main arguments
-      inputFileName = args[0];
-      outputFileName = args[1];
+    Options options = new Options();
+
+    options.addOption(OptionBuilder.withArgName("path").hasArg()
+        .withDescription("input path").create(INPUT_OPTION));
+    options.addOption(OptionBuilder.withArgName("path").hasArg()
+        .withDescription("output path").create(OUTPUT_OPTION));
+
+    CommandLine cmdline = null;
+    CommandLineParser parser = new GnuParser();
+    try {
+      cmdline = parser.parse(options, args);
+    } catch (ParseException exp) {
+      HelpFormatter formatter = new HelpFormatter();
+      formatter.printHelp(UrlMappingBuilder.class.getName(), options);
+      ToolRunner.printGenericCommandUsage(System.out);
+      System.err.println("Error parsing command line: " + exp.getMessage());
+      System.exit(-1);
     }
+
+    if (!cmdline.hasOption(INPUT_OPTION) || !cmdline.hasOption(OUTPUT_OPTION)) {
+      HelpFormatter formatter = new HelpFormatter();
+      formatter.printHelp(UrlMappingBuilder.class.getName(), options);
+      ToolRunner.printGenericCommandUsage(System.out);
+      System.exit(-1);
+    }
+
+    String input = cmdline.getOptionValue(INPUT_OPTION);
+    String output = cmdline.getOptionValue(OUTPUT_OPTION);
+
     List<String> inputValues = null;
     try {
-      inputValues = readUrlFromFolder(inputFileName); // read data
+      inputValues = readUrlFromFolder(input); // read data
     } catch (IOException e) {
       e.printStackTrace();
     }
 
     PositiveIntOutputs outputs = PositiveIntOutputs.getSingleton();
     Builder<Long> builder = new Builder<Long>(INPUT_TYPE.BYTE1, outputs);
     BytesRef scratchBytes = new BytesRef();
     IntsRef scratchInts = new IntsRef();
     for (int i = 0; i < inputValues.size(); i++) {
       if (i % 100000 == 0) {
         LOG.info(i + " URLs processed.");
       }
       scratchBytes.copyChars((String) inputValues.get(i));
       try {
         builder.add(Util.toIntsRef(scratchBytes, scratchInts), (long) i);
       } catch (UnsupportedOperationException e) {
         System.out.println("Duplicate URL:" + inputValues.get(i));
       } catch (IOException e) {
         e.printStackTrace();
       }
     }
     FST<Long> fst = builder.finish();
 
     // Save FST to file
-    File outputFile = new File(outputFileName);
+    File outputFile = new File(output);
     fst.save(outputFile);
-    LOG.info("Wrote output to " + outputFileName);
+    LOG.info("Wrote output to " + output);
   }
 }