diff --git a/packages/gen-tarball.sh b/packages/gen-tarball.sh
index 0cd7c67c..87240baa 100755
--- a/packages/gen-tarball.sh
+++ b/packages/gen-tarball.sh
@@ -1,69 +1,73 @@
 #!/bin/bash
 # Copyright (C) 2021 g10 Code GmbH
 #
 # Software engineering by Ingo Klöcker <dev@ingo-kloecker.de>
 #
 # This file is part of GPG4Win.
 #
 # GPG4Win is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation; either version 2 of the License, or
 # (at your option) any later version.
 #
 # GPG4Win is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program; if not, see <https://www.gnu.org/licenses/>.
 #
 # SPDX-License-Identifier: GPL-2.0+
 
 # Packages the current HEAD of a git repository as tarball and generates
 # a text block that can be copy and pasted into packages.current.
 
 set -e
 
 if [ -z "$1" ]; then
-    echo "Usage $0 package > snippet"
+    echo "Usage: $0 PACKAGE > snippet"
+    echo "where PACKAGE is either the name of a supported library or application, e.g. 'kleopatra',"
+    echo "or the path of a local Git repository, e.g. '~/src/kleopatra',"
+    echo "or the URL of a remote Git repository, e.g. 'https://invent.kde.org/pim/kleopatra.git'."
     exit 1
 fi
 
 package=$1
 
 case ${package} in
     */*)
-        repo=${package}
-        package=$(basename ${package})
+        repo=${package%/}
+        package=$(basename ${repo})
+        package=${package%.git}
         ;;
     kleopatra)
         repo=https://invent.kde.org/pim/kleopatra.git
         ;;
     *)
-        echo "Unsupported package '${package}'"
+        echo "Error: Unsupported package '${package}'"
         exit 1
         ;;
 esac
 
 tmpdir=$(mktemp -d -t gen-tarball.XXXXXXXXXX)
 curdate=$(date +%Y-%m-%d)
 timestamp=$(date +%Y%m%d%H%M)
 snapshotdir=${package}-${timestamp}
 tarball=${snapshotdir}.tar.xz
 
 git clone ${repo} ${tmpdir}/${snapshotdir}
 (cd ${tmpdir} && tar -cJ --exclude-vcs ${snapshotdir}) > ${tarball}
 
 checksum=$(sha256sum ${tarball} | cut -d ' ' -f 1)
 
 echo "------------------------------ >8 ------------------------------"
 echo "# ${package}"
 echo "# last changed: ${curdate}"
 echo "# by: ik"
 echo "# verified: Tarball created by ik."
 echo "file ${package}/${tarball}"
 echo "chk ${checksum}"
 echo "------------------------------ >8 ------------------------------"
 
 rm -r ${tmpdir}