diff --git a/configure.ac b/configure.ac
index 22f96f1..d7ae922 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,12 +18,21 @@
 #  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ##
 
-AC_INIT([easejs], [0.2.2], [bugs@easejs.org])
+# version string is dynamically generated
+m4_define([ver], m4_esyscmd(./tools/vergen))
+m4_if(ver, [], [m4_exit(1)])
+
+AC_INIT([easejs], [ver], [bugs@easejs.org])
 AC_CONFIG_AUX_DIR([tools])
 AM_INIT_AUTOMAKE([foreign])
 
-# provide more granular version numbers based on the above AC_INIT line
-m4_define([ver_split], m4_split(m4_translit(AC_PACKAGE_VERSION, [-], [.]), [\.]))
+# provide more granular version numbers based on the version string, using
+# the format MAJOR.MINOR.REV[-SUFFIX], where SUFFIX can itself contain
+# dashes (and often will)
+m4_define([ver_split],
+  m4_split(
+    patsubst(AC_PACKAGE_VERSION, [^\([^-]+\)-], [\1.]),
+    [\.]))
 AC_SUBST(MAJOR, m4_argn(1, ver_split))
 AC_SUBST(MINOR, m4_argn(2, ver_split))
 AC_SUBST(REV, m4_argn(3, ver_split))
diff --git a/tools/vergen b/tools/vergen
new file mode 100755
index 0000000..6e22885
--- /dev/null
+++ b/tools/vergen
@@ -0,0 +1,37 @@
+#!/bin/sh
+# Generates version string
+#
+#  Copyright (C) 2014 Free Software Foundation, Inc.
+#
+#  This file is part of GNU ease.js.
+#
+#  This program 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 3 of the License, or
+#  (at your option) any later version.
+#
+#  This program 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 <http://www.gnu.org/licenses/>.
+##
+
+# for distributions
+if [ -f version ]; then
+  cat version
+  exit
+fi
+
+git rev-parse --show-toplevel >/dev/null 2>&1 || {
+  echo 'fatal: git repository is not available'
+}
+
+version="$( git describe --match='[0-9]\.*' --abbrev=7 HEAD 2>/dev/null )"
+git update-index -q --refresh
+test -z "$( git diff-index --name-only HEAD)" || version="$version-dirty"
+
+echo -n "$version"
+