diff --git a/image.py b/image.py
index 2d05793..2efb1c8 100644
--- a/image.py
+++ b/image.py
@@ -369,7 +369,7 @@ def cmd_image():
               is_flag=True,
               default=False,
               help='Disable trying to download packages instead of building if building is enabled.')
-@click.option('--block-target', default=None, help='Override the block device file to write the final image to')
+@click.option('--block-target', type=click.Path(), default=None, help='Override the block device file to write the final image to')
 @click.option('--skip-part-images',
               is_flag=True,
               default=False,
@@ -380,7 +380,11 @@ def cmd_build(profile_name: str = None,
               no_download_pkgs=False,
               block_target: str = None,
               skip_part_images: bool = False):
-    """Build a device image"""
+    """
+    Build a device image.
+
+    Unless overriden, required packages will be built or preferably downloaded from HTTPS repos.
+    """
     enforce_wrap()
     profile: Profile = config.get_profile(profile_name)
     device, flavour = get_device_and_flavour(profile_name)
diff --git a/packages/__init__.py b/packages/__init__.py
index 49876e0..2485598 100644
--- a/packages/__init__.py
+++ b/packages/__init__.py
@@ -735,17 +735,20 @@ def cmd_update(non_interactive: bool = False):
 
 @cmd_packages.command(name='build')
 @click.option('--force', is_flag=True, default=False, help='Rebuild even if package is already built')
-@click.option('--arch', default=None, help="The CPU architecture to build for")
+@click.option('--arch', default=None, required=False, type=click.Choice(ARCHES), help="The CPU architecture to build for")
 @click.option('--rebuild-dependants', is_flag=True, default=False, help='Rebuild packages that depend on packages that will be [re]built')
 @click.option('--no-download', is_flag=True, default=False, help="Don't try downloading packages from online repos before building")
 @click.argument('paths', nargs=-1)
 def cmd_build(paths: list[str], force=False, arch=None, rebuild_dependants: bool = False, no_download: bool = False):
     """
-    Build packages by paths.
+    Build packages (and dependencies) by paths as required.
 
     The paths are specified relative to the PKGBUILDs dir, eg. "cross/crossdirect".
 
     Multiple paths may be specified as separate arguments.
+
+    Packages that aren't built already will be downloaded from HTTPS repos unless --no-download is passed,
+    if an exact version match exists on the server.
     """
     build(paths, force, arch, rebuild_dependants, not no_download)