diff --git a/src/main/java/org/RI/P2/Indexer.java b/src/main/java/org/RI/P2/Indexer.java
index f61d6c5..494f5c4 100644
--- a/src/main/java/org/RI/P2/Indexer.java
+++ b/src/main/java/org/RI/P2/Indexer.java
@@ -93,4 +93,18 @@ public class Indexer {
         }
         commitChanges();
     }
+
+    private static void usage() {
+        System.out.println("Usage: Indexer <directory>");
+        System.exit(1);
+    }
+
+    public static void main(String[] args) throws ParseException, IOException {
+        if (args.length != 1) {
+            usage();
+        }
+        String dataDirectory = args[0];
+        Indexer indexer = new Indexer(dataDirectory);
+        indexer.populateIndex();
+    }
 }