diff --git a/src/main.rs b/src/main.rs
index 2e30197..402e929 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,5 @@
 use {
-    clap::Parser,
+    clap::{Parser, Subcommand},
     geo_types::Point,
     image::{ImageBuffer, Luma},
     las::Read as LasRead,
@@ -13,26 +13,46 @@ use {
 
 mod geonb;
 
-#[derive(Parser, Debug)]
-#[clap(author, version, about, long_about=None)]
+#[derive(Parser)]
+#[command(author, version, about, long_about=None)]
 struct Args {
-    // Latitude to fetch LIDAR tile at
-    #[clap(long)]
-    latitude: Option<f64>,
-
-    // Longitude to fetch LIDAR tile at
-    #[clap(long)]
-    longitude: Option<f64>,
-
-    // Print extra debug info when initializing raphics
-    #[clap(long)]
+    /// Print extra debug info when initializing graphics
+    #[arg(long)]
     debug_init: bool,
 
-    #[clap(long)]
-    laz_file: Option<PathBuf>,
+    #[command(subcommand)]
+    command: Command,
+}
 
-    #[clap(long)]
-    grid_cell_size: Option<f64>,
+#[derive(Subcommand)]
+enum Command {
+    /// Download data from GeoNB
+    GeoNB {
+        #[command(subcommand)]
+        command: GeoNBCommand,
+    },
+    /// Create a grid DEM from point data
+    GridPoints {
+        #[arg(long, short = 'i')]
+        laz_filename: PathBuf,
+
+        #[arg(long)]
+        grid_cell_size: f64,
+    },
+}
+
+#[derive(Subcommand)]
+enum GeoNBCommand {
+    /// Download the LIDAR tile that includes a location
+    DownloadLidarTile {
+        /// Latitude to fetch LIDAR tile at
+        #[arg(long, allow_hyphen_values=true)]
+        latitude: f64,
+
+        /// Longitude to fetch LIDAR tile at
+        #[arg(long, allow_hyphen_values=true)]
+        longitude: f64,
+    },
 }
 
 trait FromFloatFloor<F> {
@@ -231,38 +251,47 @@ where
 async fn main() -> Result<(), anyhow::Error> {
     let args = Args::parse();
 
-    if let (Some(latitude), Some(longitude)) = (args.latitude, args.longitude) {
-        let location = Proj::new_known_crs("+proj=longlat +datum=WGS84", "EPSG:2953", None)
-            .unwrap()
-            .convert(Point::new(longitude, latitude))
-            .unwrap();
-        println!("{:?}", location);
-        let mut las_reader =
-            tokio::io::BufReader::new(geonb::get_lidar_tile_around_point(location).await?);
-        let mut las_bytes = Vec::new();
-        let mut buffer = [0_u8; 4096];
-        let mut byte_count = 0;
-        loop {
-            let num_bytes = las_reader.read(&mut buffer).await?;
-            if num_bytes == 0 {
-                break;
+    match args.command {
+        Command::GeoNB {
+            command:
+                GeoNBCommand::DownloadLidarTile {
+                    latitude,
+                    longitude,
+                },
+        } => {
+            let location = Proj::new_known_crs("+proj=longlat +datum=WGS84", "EPSG:2953", None)
+                .unwrap()
+                .convert(Point::new(longitude, latitude))
+                .unwrap();
+            println!("{:?}", location);
+            let mut las_reader =
+                tokio::io::BufReader::new(geonb::get_lidar_tile_around_point(location).await?);
+            let mut las_bytes = Vec::new();
+            let mut buffer = [0_u8; 4096];
+            let mut byte_count = 0;
+            loop {
+                let num_bytes = las_reader.read(&mut buffer).await?;
+                if num_bytes == 0 {
+                    break;
+                }
+                byte_count += num_bytes;
+                print!("{} bytes read\r", byte_count);
+                las_bytes.extend_from_slice(&buffer[0..num_bytes]);
             }
-            byte_count += num_bytes;
-            print!("{} bytes read\r", byte_count);
-            las_bytes.extend_from_slice(&buffer[0..num_bytes]);
+            println!();
+            let mut las_reader = las::Reader::new(std::io::Cursor::new(las_bytes))?;
+            for wrapped_point in las_reader.points().take(10) {
+                let point = wrapped_point.unwrap();
+                println!("Point coordinates: ({}, {}, {})", point.x, point.y, point.z);
+            }
+            Ok(())
         }
-        println!();
-        let mut las_reader = las::Reader::new(std::io::Cursor::new(las_bytes))?;
-        for wrapped_point in las_reader.points().take(10) {
-            let point = wrapped_point.unwrap();
-            println!("Point coordinates: ({}, {}, {})", point.x, point.y, point.z);
-        }
-    }
-
-    if let Some(laz_filename) = args.laz_file {
-        let mut las_reader = las::Reader::from_path(laz_filename).unwrap();
-        let bounds = las_reader.header().bounds();
-        if let Some(grid_cell_size) = args.grid_cell_size {
+        Command::GridPoints {
+            laz_filename,
+            grid_cell_size,
+        } => {
+            let mut las_reader = las::Reader::from_path(laz_filename).unwrap();
+            let bounds = las_reader.header().bounds();
             let num_cells_x = ((bounds.max.x - bounds.min.x) / grid_cell_size).ceil() as usize;
             let num_cells_y = ((bounds.max.y - bounds.min.y) / grid_cell_size).ceil() as usize;
             let mut height_grid = Grid::new(num_cells_y, num_cells_x);
@@ -288,8 +317,7 @@ async fn main() -> Result<(), anyhow::Error> {
                 ImageBuffer::from_raw(num_cells_x as u32, num_cells_y as u32, grid_u8.data)
                     .unwrap();
             image.save("test.png")?;
+            Ok(())
         }
     }
-
-    Ok(())
 }